By clicking one of the view buttons at the bottom of the screen, you can switch among these views:

In all three views, you can tap Today (bottom left) to return to today’s date.

The basic calendar is easy to figure out. After all, with the exception of one unfortunate Gregorian incident, we’ve been using calendars successfully for centuries.

Even so, recording an event on this calendar is quite a bit more flexible than entering one on, say, one of those “Hunks of the Midwest Police Stations” paper calendars.

Start by tapping the button (top-right corner of the screen). The Add Event screen pops up, filled with tappable lines of information. Tap one (like Title/Location, Starts/Ends, or Repeat) to open a configuration screen for that element.

For example:

When you tap Save and return to the main Add Event screen, you see that a new line, called Second Alert, has sprouted up beneath the first Alert line. This line lets you schedule a second warning for your appointment, which can occur either before or after the first one. Think of it as a backup alarm for events of extra urgency. Tap Save.

Once you’ve scheduled these alerts, you’ll see a message appear on the screen at the appointed time(s). (Even if the phone was asleep, it appears briefly.) You’ll also hear a chirpy alarm sound.

When you’ve completed filling in all these blanks, tap Done. Your newly scheduled event now shows up on the calendar.

To examine the details of an appointment in the calendar, tap it once. The Event screen appears, filled with the details you previously established.

To edit any of these characteristics, tap Edit. You return to what looks like a clone of the New Event screen shown on Making an Appointment.

Here, you can change the name, time, alarm, repeat schedule, or any other detail of the event, just the way you set them up to begin with. (Except the calendar category. For some reason, you can’t change that once you’ve set it.)

This time, there’s a big red Delete Event button at the bottom. That’s the only way to erase an appointment from your calendar.

A calendar, in Apple’s somewhat confusing terminology, is a color-coded sub-set—a category—into which you can place various appointments. They can be anything you like. One person might have calendars called Home, Work, and TV Reminders. Another might have Me, Spouse ’n’ Me, and The Kidz. A small business could have categories called Deductible Travel, R&D, and R&R.

You can’t create calendar categories, or change their colors, on the iPhone—only in your desktop calendar program. Or, if you’re a MobileMe member, you can also set up your categories at www.me.com; all your categories and color codings show up on the iPhone automatically.

What you can do, in iOS 4 for the first time, is choose which subset of categories you want to see. Just tap Calendars at the top of any Calendar view. You arrive at the big color-coded list of your categories.

This screen exists partly as a reference, a cheat sheet to help you remember what color goes with which category, and partly as a tappable subset-chooser. That is, if you tap the Work category, you return to the calendar view you were just viewing, but now all categories are hidden except the one you tapped.

The YouTube program is basically a collection of lists. Tap one of the icons at the bottom of the screen, for example, to find videos in any of these ways:

If you tap More, you get some additional options:

Each list offers a button at the right side. Tap it to open the Details screen for that video, featuring a description, date, category, tags (keywords), uploader name, play length, number of views, links to related videos, and so on.

Also on this screen are Add to Favorites, which adds this video to your own personal list of favorites (tap Favorites at the bottom of the screen to see it); Add to Playlist, which opens a Playlist screen where you can add, edit, and delete these self-playing sequences of videos; and Share Video, which creates an outgoing message containing a link to that video.

Address it and send it along to anyone you think would be interested, thus fulfilling your duty as a cog in the great viral YouTube machine.

To play a video, tap its row in any of the lists. Turn the iPhone 90 degrees counterclockwise—at least if you want to see the video full-screen. The video begins playing automatically; you don’t have to tap the button. (In iOS 4, you can turn the iPhone upright once the video starts, but that makes it play all shrunken in the screen, with huge, black, empty areas above and below.)

Here, you’ll discover a basic truth about the YouTube app on the iPhone: Videos look great if you’re connected to the Internet through a WiFi hot spot or the 3G network. They look not so great if you’re connected over AT&T’s cellular EDGE network. When you’re on EDGE, you get a completely different version of the video—smaller, coarser, and grainier. In fact, you may not be able to get videos to play at all over EDGE.

When you first start playing a video, you get the usual iPhone playback controls ( ) the volume slider, and the progress scrubber at the top. Here again, you can double-tap the screen to magnify the video slightly, just enough to eliminate the black bars on the sides of the screen (or tap the button at the top-right corner to do the same).

The controls fade away after a moment so they don’t block your view. You can make them appear and disappear with a single tap on the video.

There are two icons on these controls, however, that don’t also appear when you’re playing iPod videos. First is the button, which adds the video you’re watching to your Favorites list so you won’t have to hunt for it later.

Second is the button, which pauses the video and sends you to the Mail app, where a link to the video is pasted into an outgoing message for you.

The button at the top-left corner takes you out of the video you’re watching and back to the list of YouTube videos.

If you turn the iPhone sideways, you get a much bigger, more detailed, widescreen graph of the stock in question. (Flick horizontally to view the previous or next stock.)

Better yet, you can pinch with two fingers or two thumbs to isolate a certain time period; pop-up bubbles show you how much of a bath you took (or how much of a windfall you received) during the interval you highlighted. Cool!

It’s fairly unlikely that your stock portfolio contains just Apple, Google, and Yahoo. Fortunately, you can customize the list of stocks to reflect the companies you do own (or you want to track).

To edit the list, tap the button in the lower-right corner. You arrive at the editing screen, where the following choices await:

When you’re finished setting up your stock list, tap Done.

The very first time you open Maps, you see a miniature U.S. map. Double-tap to zoom in, over and over again, until you’re seeing actual city blocks. You can also pinch or spread two fingers to magnify or shrink the view. Drag or flick to scroll around the map.

To zoom out again, use the rare two-finger tap. So—zoom in with two taps using one finger; zoom out with one tap using two fingers.

At any time, you can tap the curling-page button in the corner of the screen () to open a secret panel of options. Here you can tap your choice of amazing map views: Map (street-map illustration), Satellite (stunning aerial photos), or Hybrid (photos superimposed with street names).

There’s no guarantee that the Satellite view provides a very recent photo—different parts of the Google Maps database use photography taken at different times—but it’s still very cool.

If any phone can tell you where you are, it’s the iPhone. It has not one, not two, but three ways to determine your location.

All right—now that you know how the iPhone gets its location information, here’s how you can use it. It does not give you GPS-like navigation instructions, with a voice saying, “Turn left on Elm Street”—at least not unless you get an app that does that from the App Store. (Most require a monthly fee, but not all; try MapQuest 4 Mobile, for example.)

What it can do, though, is show you where you are. Tap the Locate button () at the bottom of the Maps screen. The button turns blue, indicating that the iPhone is consulting its various references—GPS, WiFi network, cellular network—to try to figure out where you are.

What you see now depends on what kind of luck the phone is having (read the illustration below from right to left):

It’s great to see a blue pin on the map, and all—but how do you know which way you’re facing? Legions of iPhone fans have developed a peculiar ritual known as the iPhone Circle, in which they run the perimeter of an imaginary 50-yard circle, holding out the iPhone before them, in an attempt to figure out which way is up on the map.

If you have an iPhone 3GS or iPhone 4, you don’t have to bother. Thanks to the built-in magnetometer (compass), the map can orient itself for you.

Just tap the button twice. The map spins so that the direction you’re facing is upward. A “flashlight beam” emanates from your blue dot; its width indicates the iPhone’s degree of confidence. (The narrower the beam, the surer it is.)

You’re not always interested in finding out where you are; often enough, you know that much perfectly well. Instead, you want to see where something else is. That’s where the Search button comes in.

Tap it to summon the Search box and the iPhone keyboard. (If there’s already something in the Search box, tap the button to clear it out.)

Here’s what Maps can find for you:

When Maps finds a specific address, an animated, red-topped pushpin comes flying down onto its precise spot on the map. A translucent bubble identifies the location by name.

Maps is also plugged into your Contacts list, which makes it especially easy to find a friend’s house (or just to see how ritzy his neighborhood is).

Instead of typing an address into the empty Search bar, tap the button at the right end of it. You arrive at the Bookmarks/Recents/Contacts screen, containing three lists that can save you a lot of typing.

Two of them are described in the next section. But if you tap Contacts, you see your master address book (Chapter 3). Tap the name of someone you want to find. In a flash, Maps drops a red, animated pushpin onto the map to identify that address.

That pushpin business also comes into play when you use Maps as a glorified national Yellow Pages. If you type, for example, pharmacy 60609, those red pushpins show you all the drugstores in that Chicago Zip code. It’s a great way to find a gas station, a cash machine, or a hospital in a pinch. Tap a pushpin to see the name of the corresponding business.

As usual, you can tap the button in the map pin’s label bubble to open a details screen. If you’ve searched for a friend, then you see the corresponding Contacts card. If you’ve searched for a business, then you get a screen containing its phone number, address, Web site, and so on. Remember that you can tap a Web address to open it, or tap a phone number to dial it. (“Hello, what time do you close today?”)

In both cases, you get two useful buttons, labeled Directions To Here and Directions From Here. Turn the page for details.

You also get buttons like Add to Bookmarks and Create New Contact, which save this address for instant recall (read on).

Let’s face it: The iPhone’s tiny keyboard can be a little fussy. One nice thing about Maps is the way it tries to eliminate typing at every step.

If you tap the button at the right end of the Search bar, for example, you get the Bookmarks/Recents/Contacts screen—three lists that spare you from having to type stuff.

If you tap Directions, the Search bar turns into two Search bars: one labeled Start and the other, End. Plug in two addresses—if you’ve used the Location function, the Start address already says “Current Location”—and let Google Maps guide you from the first to the second.

The iPhone does give you turn-by-turn directions—but only as written instructions on the screen, not as a spoken voice. Also, you have to ask for each successive instruction; this app doesn’t display them automatically based on your current position. It’s not a Garmin, in other words.

Still, for a phone, it’s not bad.

Begin by filling in the Start and End boxes. You can use any of the address shortcuts on pages 215-216, or you can tap to specify a bookmark, a recent search, or a name in Contacts. (Or, after performing any search that produces a pushpin, you can tap the button in its label bubble and then tap Directions To Here or Direction From Here on the details screen.)

Then tap Route. In just a moment, Maps displays an overview of the route you’re about to drive. At the top of the screen, you see the total distance and the amount of time it’ll take (if you stay within the speed limit). Amazingly, you also see buttons for (public transportation) and (walking) directions. These usually take you longer, and public transport isn’t always available, but it’s amazing that they’re even an option.

Tap Start to see the first driving instruction. The map also zooms in to the actual road you’ll be traveling, which looks like it’s been drawn in with purple highlighter. It’s just like having a printout from MapQuest—the directions at the top of the screen say, for example, “Head east on Canterbury Ln toward Blackbird Ave – go .5 mi.” Unlike MapQuest, though, you see only one instruction at a time (the current step)—and you don’t have to clutch and peer at a crumpled piece of paper while you’re driving.

Tap the or buttons to see the previous or next driving instruction. At any time, you can also tap and then List to see the master list of turns. Tap an instruction to see a closeup of that turn on the map.

To adjust one of the addresses, tap the current driving instruction; the Search boxes reappear. And to exit the driving mode, tap the button again.

How’s this for a cool feature? Free, real-time traffic reporting—the same information you’d have to pay Sirius XM Satellite Radio $10 a month for. Just tap (lower-right corner), and then tap Show Traffic. Now the stretches of road change color to indicate how bad the traffic is.

If you don’t see any color-coding, it’s because Google doesn’t have any information for those roads. Usually, the color-coding appears only on highways, and only in metropolitan areas.

OK, if your brain isn’t already boggled by the iPhone, this’ll do it.

Most people think of Google Maps as an overhead view, like any other map. But these days, there’s more to it than that. And it’s all lurking in the little icon. Look for him on the red pushpin label after any search. He’s likely to appear whenever you search for a street address in a suburb or city (or when you search for the city itself).

When you tap this guy, you open up Street View. It’s a 360-degree photographic view of the entire area at street level. You can actually perform a virtual walk-through of an entire city this way! The illustration below tells you all you need to know.

What a great way to check out a neighborhood before you visit, shop—or move—there.

You might not guess that such a tiny, self-effacing app might actually offer some basic editing functions, but it does. Tap the button to the right of any recording to open its Info screen.

Here, you can give yourself some clue what it is by choosing a label (Podcast, Interview, and so on, shown on the facing page at left). Or tap Custom and type in any name you prefer.

If you tap Trim Memo, you get the display shown below at right. Drag the endpoints of the scroll bar inward to cut the dead air off the beginning and end, playing the sound as necessary to guide you (). Tap Trim Voice Memo.

The iPhone can synchronize your collection of notes with all kinds of other notes sources, so the same notes are waiting for you everywhere you look.

For example, most email programs let you create notes. To that end, you can set up iTunes to sync your iPhone notes with Mail (Apple’s email program for the Mac) or with Microsoft Outlook 2003, 2007, or 2010 on a PC. The “Two-Mailbox Problem” has the details.

Your notes can also sync wirelessly with the Notes modules on MobileMe, Google, Yahoo, AOL, or another IMAP email account. To set this up, open Setings→Mail, Contacts, Calendars. Tap the account you want (MobileMe, Gmail, Yahoo, AOL, or whatever); finally, turn the Notes switch On.

That should do it. Now your notes are synced, both ways, with Mail or Outlook when you connect the iPhone to your computer with the cable.With a MobileMe account, notes are synced nearly instantly, wirelessly, both directions.

One catch: Notes you create at gmail.com, aol.com, or yahoo.com don’t wind up on the phone. Those accounts sync wirelessly in one direction only: from the iPhone to the Web site, where the notes arrive in a Notes folder. (There’s no problem, however, if you get your AOL or Gmail mail in an email program like Outlook or Gmail. Then it’s two-way syncing as usual.)

When you tap World Clock on the Clock screen, you start out with only one clock, showing the current time in Apple’s own Cupertino, California.

The neat part is that you can open up several of these clocks, and set each one up to show the time in a different city. The result looks like the row of clocks in a hotel lobby, making you look Swiss and precise.

By checking these clocks, you’ll know what time it is in some remote city, so you don’t wind up waking somebody up at what turns out to be 3 a.m.

To specify which city’s time appears on the clock, tap the button at the upper-right corner. The keyboard pops up so you can type the name of a major city. As you type, a scrolling list of matching city names appears above the keyboard; tap the one whose time you want to track.

As soon as you tap a city name, you return to the World Clock display. The color of the clock indicates whether it’s daytime (white) or night (black). Note, too, that you can scroll the list of clocks. You’re not limited to four, although only four fit on the screen at once.

To edit the list of clocks, tap Edit. Delete a city clock by tapping and then Delete, or drag clocks up or down using the as a handle. Then tap Done.

If you travel much, this feature could turn out to be one of your iPhone’s most useful functions. It’s reliable, it’s programmable, and it even wakes the phone first, if necessary, to wake you.

To set an alarm, tap Alarm at the bottom of the Clock program’s screen. Tap the button at the upper-right corner to open the Add Alarm screen.

You have several options here:

When you finally tap Save, you return to the Alarm screen, which lists your new alarm. Just tap the On/Off switch to cancel an alarm. It stays in the list, though, so you can quickly reactivate it another day, without having to redo the whole thing. You can tap the button to set another alarm, if you like.

Note, too, that the icon appears in the status bar at the top of the iPhone screen. That’s your indicator that the alarm is set.

To delete or edit an alarm, tap Edit. Tap and then Delete to get rid of an alarm completely, or tap the alarm’s name to return to the setup screen, where you can make changes to the time, name, sound, and so on.

So what happens when the alarm goes off? The iPhone wakes itself up, if it was asleep. A message appears on the screen, identifying the alarm and the time.

And, of course, the sound rings. This alarm is one of the only iPhone sounds that you’ll hear even if the silencer switch is turned on. Apple figures that if you’ve gone to the trouble of setting an alarm, you probably really want to know about it, even if you forget to turn the ringer back on.

In that case, the screen says, slide to stop alarm.

To cut the ringing short, tap OK or Snooze, or press the Sleep switch, or tap a volume button. After the alarm plays (or you cut it short), its On/Off switch goes to Off (on the Alarm screen).

You’ve never met a more beautiful stopwatch than this one. Tap Start to begin timing something: a runner, a train, a long-winded person who’s arguing with you.

While the digits are flying by, you can tap Lap as often as you like. Each time, the list at bottom identifies how much time elapsed since the last time you tapped Lap. It’s a way for you to compare, for example, how much time a runner is spending on each lap around a track.

(The tiny digits at the very top measure the current lap.)

You can do other things on the iPhone while the stopwatch is counting, by the way. In fact, the timer keeps ticking away even when the iPhone is asleep! As a result, you can time long-term events, like how long it takes an ice sculpture to melt, the time it takes for a bean seed to sprout, or the length of a Michael Bay movie.

Tap Stop to freeze the counter; tap Start to resume the timing. If you tap Reset, you reset the counter to zero and erase all the lap times.

The fourth Clock mini-app is a countdown timer. You input a starting time, and it counts down to zero.

Countdown timers are everywhere in life. They measure the time of periods in sports and games, of cooking times in the kitchen, of stunts on Survivor. But on the iPhone, the timer has an especially handy function: It can turn off the music or video after a specified amount of time. In short, it’s a Sleep timer that plays you to sleep, then shuts off to save power.

To set the timer, open the Clock app and then tap Timer. Spin the two dials to specify the number of hours and minutes you want to count down.

Then tap the When Timer Ends control to set up what happens when the timer reaches 0:00. Most of the options here are ringtone sounds, so you’ll have an audible cue that the time’s up. The top one, though, Sleep iPod, is the aforementioned sleep timer. It stops audio and video playback at the appointed time, so that you (and the iPhone) can go to sleep. Tap Set.

Finally, tap Start. Big clock digits count down toward zero. While it’s in progress, you can do other things on the iPhone, change the When Timer Ends settings, or just hit Cancel to forget the whole thing.

To shop the iBooks bookstore, open the iBooks app. Tap Store in the upperright corner. Here’s the literary equivalent of the App Store, complete with the icons across the bottom. Tap Featured to see what Apple’s plugging this week; Browse to see the most popular books in each category (tap Categories at top left to specify which category); Charts to see this week’s bestsellers, including what’s on the New York Times Best Seller list; Search to search by name; and Purchases to see what you’ve bought.

Once you find a book that looks good, you can either tap Get Sample to download a free chapter, read ratings and reviews, or tap the price itself to buy the book and download it straight to the phone.

Apple’s bookstore isn’t the only way to get books. You can also load up your ebook reader from your computer, feeding it with PDF documents and ePub files.

As usual, iTunes is the most convenient loading dock for files bound for your iPhone. Open the program on your Mac or PC. Click Books in the Library list at the left side. Here you’ll see all the books, PDF documents, and ePub files that you’ve slated for transfer.

To add to this set, just drag files off of your desktop and directly into this window, as shown here.

And where are you supposed to get all these files? Well, PDF documents are everywhere—people send them as attachments, and you can turn any document into a PDF file. (For example, on the Mac, in any program, choose File→Print; in the resulting dialog box, click PDF→Save as PDF.)

But free ebooks in ePub format are everywhere, too. There are 33,000 free downloadable books at gutenberg.org, for example, and over a million at books.google.com—oldies, but classic oldies, with lots of Mark Twain, Agatha Christie, Herman Melville, H.G. Wells, and so on.

Once you’ve got some books loaded up in iTunes, you specify which ones you want synced to the phone by connecting the iPhone, clicking its icon in the list at left, clicking the Books tab at top, and turning on the checkboxes of the books you want to transfer. (Details are on The Podcasts & iTunes U Tabs.)

Once you’ve supplied your iBooks app with some reading material, the fun begins. When you open the app, you see a handsome wooden bookshelf, with your own personal library represented as little book covers. Mostly what you’ll do here is tap a book to open it. But there are all kinds of other activities waiting for you:

But come on—you’re a reader, not a librarian. Here’s how you read an ebook.

Open the book or PDF by tapping the book cover. Now the book opens, ready for you to read. Looks great, doesn’t it? (If you’re returning to a book you’ve been reading, iBooks remembers your place.)

In general, reading is simple: Just read. Turn the page by tapping the edge of the page—or swiping your finger across the page. (If you swipe slowly, you can actually see the “paper” bending over—in fact, you can see through to the “ink” on the other side of the page! Amaze your friends.) You can tap or swipe the left edge (to go back a page) or the right edge (forward).

But if you tap a page, a row of additional controls appear:

When you’re reading a PDF document, by the way, you can do something you can’t do when reading regular books: zoom in and out using the usual twofinger pinch-and-spread gestures. Very handy indeed.

Here are some more stunts that you’d have trouble pulling off in a printed book. If you hold your finger down on a word, you get this effect:

There are a couple of cool things going on with your bookmarks, notes, and highlighting, by the way. Once you’ve added them to your book, they’re magically and wirelessly synced to any other copies of that book—on other gadgets, like the iPad or iPod Touch (or other iPhones). Very handy indeed.

Furthermore, if you tap the button to open the Table of Contents, you’ll see a Bookmarks tab. It presents a tidy list of all your bookmarked pages, notes, and highlighted passages. As usual, tap a page to jump there.