According to wikipedia's definition "a sitemap is a list of pages of a website accessible to crawlers or users (...) organized in hierarchical fashion." source
WHY YOUR WEBSITE SHOULD HAVE A SITEMAP
Adding a sitemap does not affect search rankings. However by having a sitemap properly included into your site searchengine spiders will find all content on your site and index it.
The sitemap tells the spiders how often the page is updated and help them to crawl your site more efficiently. The XML sitemap is not intended for humans to read so to improve your site's usability you can also create a custom sitemap template and link it in the footer or show it on 404 error pages. List the latest posts and pages in hierarchical order.
HOW TO MAKE A SITEMAP
NINJA TRICK: SUBMIT YOUR RSS FEED
Your RSS feed is also in XML format and can be submitted as a sitemap too. Bing and google encourage you to add your feed too. Their spiders can grab the latest content. The XML sitemap is a complete snapshot of your site and the feed contains the most recent updates. More data for searchengines to keep their index up-to-date.
<?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> <url> <loc>http://www.yourwebsite.com</loc> <lastmod>2013-01-01</lastmod> <changefreq>weekly</changefreq> <priority>0.9</priority> </url> <url> <loc>http://www.yourwebsite.com/articles/100</loc> <changefreq>weekly</changefreq> </url> <url> <loc>http://www.yourwebsite.com/articles/101</loc> <lastmod>2013-01-02</lastmod> <changefreq>weekly</changefreq> </url> <url> <loc>http://www.yourwebsite.com/articles/102</loc> <lastmod>2013-01-02T13:00:12+00:00</lastmod> <priority>0.5</priority> </url> </urlset>
- Is your sitemap valid? Test it here
- Avoid dublicate urls
- Keep sitemaps and feed to a minimum (best: 1 sitemap + 1 feed)
- Is the full url added to robots.txt?
- Have you submitted it to google+bing webmaster tools?
- Only list your homepage, pages and posts - there`s no need to add tags and categories. Those pages won't show up new urls as they are already listed via posts\pages
- Do not list more than 50.000 urls in one sitemap
- Only include URLs that can be fetched by searchengines and are not blocked by robots.txt or meta robots
- Only include canonical URLs