what is sitemap,and what's the use of it,how to make one, dose a blog need it? hope who can tell me .thanks
If you read the sticky at the top of this forum I think all your questions will be answered. In case you missed it here is the url http://forums.digitalpoint.com/showthread.php?t=531765.
The simplest way would be to use http://www.web-site-map.com/ online generator. It handles Joomla quite nicely.
I use xmap, a very popular extension for Joomla: http://extensions.joomla.org/extensions/structure-a-navigation/site-map/3066
Sitemap are great to let search engines know about your urls and what to index. You can use xml sitemap for generating structured and SEO friendly sitemap. Go to xml-sitemaps dot com. Or if you are using CMS, then you can download free plugins to generate sitemaps automatically.