Sitemaps is, essentially, free XML inclusion. The kind of service previously offered by Inktomi and AskJeeves and now offered (in part) by Yahoo! Search Marketing Solutions. The service allows web site owners to place an XML file on their site containing links to all the pages that they want Google to see. Google will then use this sitemap to help to help it determine the pages it still needs to index. In addition, the XML sitemap file can tell Google how often the page is updated, and the date on which the page was last changed.
Now, Google has a history of copying competitor’s services and going one better (something I like to call the Branson strategy) and Sitemaps is no exception. Although very similar to current and previous XML inclusion services, Google’s has many differences.
Firstly, XML inclusion lets you specify the title and description that appears in search results. With Google Sitemaps you can’t do this and because Google separately determines itself which parts of the site to crawl and how to rank the site, you get no benefit in search results by using Sitemaps.
Obviously, the main advantage with Google Sitemaps is that its completely free, whereas Yahoo’s Search Submit program requires an inclusion fee and a small charge for each click you receive. Such a huge difference begs the question of why Google would offer this for free. The answer is simple – Google’s aim is not to make money, but to organize the worlds information, and if offering free XML inclusion helps, then so be it (of course, they could make money as well, but they’re just too nice).
There are problems with Google Sitemaps, as pointed out by a number of people, but every new system has its downfalls which I’m sure will be ironed out over time. If you aren’t very technical you could be a bit confused by the whole thing, but there is help out there, and if you’re tech-savvy there is plenty to be getting on with, like plugins for Sitemaps. It’s probably a good idea to get a Google Web/News Alert for Sitemaps, in fact to help you along.