This section contains a summary of the typographic styles we use throughout the text to identify various entities, including a list of our file extension conventions.

1. An italic font like this is used for technical terms (and possibly variations thereof) that are appearing either for the first time, or later in a different context, or perhaps to call your attention to the term again for some reason, as well as for emphasizing ordinary words like this. The reader should have no difficulty in telling from the context which usage is in effect.

2. A bold font like this is used from time to time for a longer passage that is of particular importance, either in context, or for the longer term. It may also be used to emphasize the name of a software program, like HTML-Kit, or the name of an organization or company, like W3C or Microsoft, and help it to stand out from the surrounding text in a particular context, if required. This font is also used to refer to other sections of the text, such as References.

3. A typewriter-like monospaced font like this is used for all code, for showing input to and output from programs, for links, for keystroke shortcuts, and for showing contents of text files.

4. A bold sans-serif font like this is used for top-level menu choices and submenu choices.

5. Each figure in the text that shows either the full or partial contents of a file, the display of a file as it would appear in a browser window, or a diagram, is accompanied by two pieces of information:

   • The full pathname of the relevant file (including the files that are display images)

   • A caption detailing the (possibly partial) contents of the file (or what the display image is showing you)

   All of these files are available from the book’s website.

6. Table 1 shows the file extension conventions that we will follow in this text to refer to its associated files. Most markup and source code files will have the name of the file in a comment line at or near the beginning of the file. This first file-naming comment line may be accompanied by a second comment on one or more lines, indicating briefly the nature or purpose of the file content. Exceptions to this convention are those very simple files we use to begin the discussion of some topics.

   File Contents	File Extension
   Ordinary text	.txt
   HTML markup	.html
   Cascading Style Sheets	.css
   JavaScript code	.js
   PHP code	.php
   XML markup	.xml
   A textfile containing comma-separated values	.csv
   A textfile containing SQL commands	.sql
   An image file, usually a screen capture	.jpg
   A zip file	.zip