In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: "Most websites define a robots.txt file to let robots know any restrictions about crawling their website."

A block of code is set as follows:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url><loc>http://example.webscraping.com/view/Afghanistan-1</loc></url>
  <url><loc>http://example.webscraping.com/view/Aland-Islands-2</loc></url>
  <url><loc>http://example.webscraping.com/view/Albania-3</loc></url>
  ...
</urlset>

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

def link_crawler(..., scrape_callback=None):
         …
         links = []
    if scrape_callback:
        links.extend(scrape_callback(url, html) or [])
         ...

Any command-line input or output is written as follows:

$ python performance.py 
Regular expressions: 5.50 seconds
BeautifulSoup: 42.84 seconds
Lxml: 7.06 seconds

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: " When regular users open this web page in their browser, they will enter their e-mail and password, and click on the Log In button to submit the details to the server."