I've read through a number of threads on site point regarding this but none really addressed or answered the query I have. Hopefully someone here will be able to advise ...
The site I'm currently building is 'regionalised'. This means that on first visit, the user selects their region and the site customises the content depending on that selection. The users region is stored in a cookie.
I'm concerned with the impact this might have on search engine indexing.
Since we're using php, if the user doesn't have cookies enabled a session id will be automatically included in the URL. This also has a negative affect on indexing so we can't just rely on this mechanism to take care of things.
What I've done in the past, and this is legit with search engines as far as i know, is to put a script at the top of the page which checks if the visitor is a bot.
If it isn't then include the session_start() command which assigns the session ID.
If it is a search engine then the session won't be started and there will be no ids appended to your urls.
Equally you can direct the search engine to just one regions content thus avoiding getting any duplicate content penalties.