Websites can have two types of sitemaps: HTML and XML. The HTML version is for human visitors. Our Article Archives by Date is an example. And, XML sitemaps are for webbots, like the Googlebot. These are web crawling bots (or 'spiders') that discover new and updated pages to be added to the Google index.
Do you need an XML Sitemap? There is some debate about this. But, having designed and/or maintained scores of websites, I can assure that you get listed on Google faster by having one. If you have a new site and want Google to find it right away, you really need to have a Sitemap. And, if every page/post is not linked to elsewhere in your blog, it helps there too.
This does NOT, however, affect ranking in the search index. But, there are other advantages.
For instance, by submitting a Sitemap (note the capital “S”) and using Google’s Webmaster Tools, you can see how the Googlebot is indexing your site, how many pages it indexes, and any problems that it encounters. Plus, you can instruct it to visit and spider your site more or less often.
Creating an XML Sitemap
So, how do you create an XML Sitemap for your blog? If you have a single site installation, you can use the standard plugin, Google XML Sitemaps. With this plugin, there are several options available from the Dashboard (Settings -> XML-Sitemap).
You can generally accept all of the default settings. This includes automatically submitting your updated Sitemap whenever you publish a new post/page or update an existing one. Plus, it will submit to Google, Bing, Ask, and Yahoo!
Creating an XML Sitemap for Multisites
This standard plugin does NOT work with MU or 3.0+ sites with the multisite option enabled. There are numerous thread's on the author's support forum about failed attempts. So … what are those of us to do who have several blogs/sites conveniently running on the same WP installation?
The solution … and a very good one … is Google XML Sitemaps with Multisite Support. The author, Mario Kostelac, has developed a parallel project based on the standard version. In a nutshell, his working multisite version succeeds by putting all of your Sitemaps into a single directory that you create.
Other than fully supporting the multisite option, Mario's version, works exactly like the standard version. In fact, he left the donation component in tact for the author of the original, standard version … a classy decision.
Using Google's Webmaster Tools
Google’s Webmaster Tools will first ask you to add your site. For WP blogs, it's important that you NOT include the WWW in your domain name, unless you have customized your WP installation. And, after the Googlebot has spidered your site, you should check to make sure there aren't any broken links. If so, of course, you should fix them and update your Sitemap.
The Webmaster Tools Dashboard offers info beyond that directly related to the XML Sitemap. More notable of these is the “Keywords” component (Manage -> Dashboard -> Your Site on the Web -> Keywords). Here you can view a table of the ranked significance (frequency of use) of keywords the bot determined from your site.
You may want to check these keywords for your blog's niche with another quite useful Google tool, Google Adwords: Keyword Tool. Using this utility, you can target your keywords based on Google's own historical search data! This can be very helpful in moving up in the Google index. In fact, there many 3 to 5 page web sites which were built to target an audience based on reports from this Keyword Tool !
Another Google Webmaster Tool you should check out is Google Analytics. After you insert some basic code in the footer of your site, you'll have access to a wide range of traffic analysis data.
Each of these Google webmaster tools … Sitemap Tool, Keyword Tool, and Traffic Analysis … is free for you to use.