Why do some sites have several types of sitemap?

[McTaggart]

Hello Mozzers, I often seem to work on websites with several types of sitemaps - e.g. an html sitemap - an xml sitemap - almost always with identical structure and content. Does anybody know the thinking behind this?

Currently looking at site with php and xml sitemap sitting alongside one another. I'm guessing one is for site users to read (and also to aid indexing) and the other for search engines, to further aid indexing.

Does Google have any preferences? Is there anything you should be wary of re: Google, if there are multiple sitemaps?

[crackingmedia]

Hi Luke

HTML sitemaps are suitable for humans because you can then put them up as a HTML page that can be viewed and clicked from. XML sitemaps are really for search engines and are the standard that Google, Bing and Yahoo all prefer. See more info here:

http://en.wikipedia.org/wiki/Sitemap#XML_Sitemaps

I hope that helps,
Peter

[McTaggart]

Thanks Peter - I'm used to seeing .html and .xml sitemaps but not .php - do you know whether a .php sitemap is a problem in any way?

[crackingmedia]

Hi Luke

PHP is a scripting language not a sitemap format.

If you mean a PHP page, e,g sitemap.php showing a sitemap with clickable links then that will be the same as an HTML sitemap - so good for humans but not the ideal for search engines.

You can get PHP sitemap generators, but that means that they will generate a sitemap by using PHP scripting rather than creating a PHP sitemap.

I hope that helps,
Peter

[McTaggart]

Thanks for the clarification Peter - appreciated! Luke