Stack Exchange posts have URLs like this:
http://webmasters.stackexchange.com/questions/9848/squeezing-all-the-seo-out-of-a-url-as-possible
Which is the format: /questions/{id}/{slugified-post-title}
The 9848 is obviously the unique identifier of the post, which is all that is necessary to look up the question in a data source. What is the title there for then? Is it strictly for SEO reasons and maybe to make the URL more readable? Or are there other reasons as well?
Well, firstly, it does make the URL more readable. i.e. A URL such as mysite.com/pianos is a lot more informative than a URL such as mysite.com/?id=2347. To your common user, 2347 doesn't mean anything. It is random gibberish. The numerical ID-based URL doesn't give any indication about the type of content that is on the page. If a user decides to copy and paste a link to your page on another website, the slug-based URL will at least give them some sort of idea about the type of content that is being linked to.
Secondly, many users will share your content by copying and pasting the link, without much care for anchor text. In these cases, the link itself becomes the anchor text. If the slug contains keywords that are relevant to the page, and this link is "raw pasted" onto a forum, the keywords in said link will be interpreted by Google. This is evident by Webmaster Tools, which has a section called "How your content is linked." In this scenario, http://mysite.com/pianos becomes http mysite com pianos, whereas the ID-based URL becomes http mysite com id 2347.
Thirdly: There's CTR (Click Through Rate). If a user is searching for a specific keyword on Google and that keyword appears in the URL, are they more likely to click on that URL? From what I've read / experienced, the answer is yes.
Lastly, the title is there because:
