I’ve already posted about Google Sitemaps in:
Google Sitemaps, and wordpress blog tool and Improve Your Search Engine Ranking with Google Sitemaps and PHPBB
where I give examples of the code that I used to create a google sitemaps from wordpress and from PHPBB forums.
With google sitemaps, which provide a way for Google to index your site easier, it provides a way for you to record the priority of the pages. This won’t affect how your site compares with other web sites on the Internet, but helps you to prioritise pages in your google results.
When I first wrote the scripts I was thinking from the point of view of the webmaster wanting to attract visitors to the site. As a webmaster I see the top levels of my site as being the places I’d like visitors to come in from, so I chose the main index page as highest priority, the category index pages as my next priority and downwards so that the individual blog entries and forum posts were ranked quite low in the google priority. As a webmaster this seamed pretty logical.
Something I do is to monitor how my sites are ranked in google, the things they are searching on, and where they end up on my site. The thing that I realised is that people end up at my sites by searching for something specific. For example when looking at my WatkissOnline.co.uk site one of the things I include are some tourist attractions suitable for children and babies. These are links to blog entries which will end up across several different pages. So for example, when the entry for the Donkey Sanctuary in Devon was first posted, it appeared on the WatkissOnline Main Index Page, the current blog summary page, a page listing tourist attractions for children and babies, the month in which it was posted (September 2006), and a couple of different categories including the babies category, in addition to the actual post itself Tourism: Donkey Sanctuary, Sidmouth, Devon.
If the Google indexes these immediately, and a user performs a search, then the priority of the sitemap means that they will most likely end up on the main index page of the site. Assuming this is the same day as the posting then that is fine, as the user will see what they are expecting. If however another post has been made in the meantime then that particular post will have been relagated to a short summary menu, or if over 5 posts have been made then there may be no reference to that page at all. So therefore users coming to the site hoping to find out about the Donkey Sanctuary may see the index page, wonder why they got sent to a page that is not relevant to their search and go to the next item in their Google search. A simliar thing will happen if they end up at the blog main index page, which only holds about 10 entries (incidently whilst writing this the entry is the very last entry on the blog index page, so it is likely to have already moved to the 2nd page by the time I publish this post).
So to ensure that your visitors get what they expect, and to try and maximise the number of visitors that stay on the site then it may be better to actually give priority the opposite way around, so that the post is actually the highest priority.
This is relevant here because we are talking about a dynamic site, with a lot of frequent postings, where a single posting could be embedded in multiple pages. If however you have a static site, then you may want to stick to having the main index pages as the highest priority to try and present the most relevant information to your visitors.
The important thing is whenever you design a site, as well as thinking from the point of view of the webmaster, you also need to think about what your visitors are seeing, and what they are expecting from the site. Remember your favourite page is not neccessarily going to be what your visitors are looking for.