sitemap

A  sitemap  is a list of pages on a website.

Navigability
It can be easier to find the content you're looking for on a sitemap, since they are typically text-heavy pages and do not require navigating through a site which may be loading lots of Javascript or image content.

Organization Examples
Examples of corporate or other organization sites with sitemaps.
 * https://www.apple.com/sitemap/
 * http://www.ibm.com/sitemap/us/en/
 * http://www.microsoft.com/en-us/sitemap.aspx
 * http://www.w3.org/Consortium/siteindex.html

Subsites
Some sites have subsites, e.g. at subdomains, which have their own sitemaps.

Yahoo (note the inconsistent paths and presentations)
 * https://my.news.yahoo.com/sitemap/
 * http://finance.yahoo.com/sm

Past Examples

 * Google used to have a sitemap at http://www.google.com/sitemap.html however that now redirects to http://www.google.com/about/products/ which still resembles a sitemap but it's not clear if that's its intent (judging by the renaming)

sitemap microformat
See http://microformats.org/wiki/sitemap for the effort to develop a sitemap microformat to markup visible sitemap pages for semantic crawling and indexing, eliminating any need for a separate XML sitemap sidefile.

XML sitemap
There is also an XML sitemap file format:
 * http://sitemaps.org/
 * http://en.wikipedia.org/wiki/Site_map#XML_Sitemaps

However, this XML sitemap file is a sidefile that is subject to the same risks of feed files.

XML sitemap indexing
Google Webmaster Tools suggests creating an XML file in the sitemaps.org format and submitting it with the claim that their crawler can "more intelligently crawl your site". Despite that, they also say that using a sitemap "doesn't guarantee you that all the web pages listed in your sitemap can be crawled or indexed".

XML sitemap unnecessary
On 2014-12-18, discovered that his sitemap.xml file had been empty, with no idea of how long it had been empty. Despite that, his content continues to be indexed by Google.

IndieWeb XML sitemaps

 * http://bret.io/sitemap (XML)