Some time ago a friend asked me if Google would rank higher pages with .html extension rather than .php. He had read in a Forum someone stating that .html pages would get indexed faster than .php ones.

This kind of assumptions are very frequent. In this case we should ask ourselves how can we get to this conclusion. Did we test both? They were tested in exactly the same conditions?

While not 100% sure that Google looks at pages with different extensions the same way, I can tell that I have no experience of different levels of trust based on the extension of the page.

What Google really doesn't like those Session IDs on the URLs very common on Forums, for instance.

And why doesn't Google like those Session IDs?

Because he finds the same exact content following different URLs. Different Session IDs means different URLs for the same page. This is a very common characteristics on spammy sites and it raises a flag that can reduce the visibility of our website on the SERPs

But that's all!

If you have any question of the way Google indexes the pages, we should test test and test