This information is for webmasters using database driven content management systems, if you create your own website and database, then the following does not apply to your situation and you’ll want to read our section on online sitemap generators.
Sitemap Plugin for WordPress, Extensions for Joomla or Modules for Drupal, they all run inside your website. These programs look at the database to gather information about what should be included in your sitemap.
Because they run from within your website, they are extremely fast in comparison to online (external) XML Sitemap programs. However, that speed comes with a price, the price of seeing your site as a search engine bot would.
For example, say that you reference an article that doesn’t exist or a page that has invalid code, your WordPress sitemap plugin is not going to catch the error. Perhaps you have invalid redirects in your htaccess file or other problem that can’t be found by scanning the database, in such cases, Modules, Plugins and Extensions just won’t catch it.
So what’s the solution? Depending on how often you modify your website, use the external program (online sitemap generator) to periodically verify your site is error free while using the module, plugin or extension to updates XML Sitemaps as content is added.
For example, a great WordPress Sitemap Plugin would be Google XML Sitemaps by Arne Brachhold while an excellent online tool (and great for seo as well) would be AuditMyPC.com’s XML Sitemap tool. AuditMyPC’s tool is going to find errors that Brachhold’s plugin missed, but is slower on very large sites. Note: if you are using multiple WordPress blogs on one site, then you’ll want AuditMyPC.com’s tool for the correct wordpress multi site sitemap.
Both these programs are completely free, have been proven time and time again and regularly updated. Whichever software you choose, make sure your site is error free BEFORE submitting your sitemap.