The document discusses URLs and links. A URL contains a scheme, host name, port number, hierarchical portion, query, and fragment. An <a> tag is used to create links and can reference a full URL, relative location within the same site, absolute location within the same site using a leading slash, or an anchor on the same page using a hashtag.

1. CS 142 Lecture Notes: URLs and Links Slide 1
Uniform Resource Locators (URLs)
http://www.company.com:81/a/b/c.html?user=Alice&year=2008#p2
Scheme
Host Name
Port Number
Hierarchical portion
Query
Fragment

2. CS 142 Lecture Notes: URLs and Links Slide 2
<a> Examples
● Full URL:
<a href="http://www.xyz.com/news/2009.html">2009 News</a>
● Relative location:
<a href="2008/March.html">
same as http://www.xyz.com/news/2008/March.html
● Absolute location in same site:
<a href="/stock/quote.html">
same as http://www.xyz.com/stock/quote.html
● New location, same page:
<a href="#sec3">
● Anchor definition:
<a name="sec3">...</a>

3. CS 142 Lecture Notes: URLs and Links Slide 3