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Usage guidance, also known as a tag wiki excerpt, is a short blurb that describes when and why a tag should be used on this site specifically.
A sitemap is an easy way for webmasters to inform search engines about pages on their sites that are available for crawling. The sitemap protocol format is defined at http://www.sitemaps.org/protocol.html
Sitemap can be either a document in any form used as a planning tool for web design, or a web page that lists the pages on a web site, typically organized in hierarchical fashion. This helps visitors and search engine bots find pages on the site.