Using PHP, is it possible to detect what browser and OS the user is using, and store this information inside a database.
Browser/OS Type
It is possible to detect what the user's browser claims to be its type and OS, but there is no guarantee that either piece of information will be received or that it is correct. You can parse the $_SERVER['HTTP_USER_AGENT'] string to see what info the browser has sent (if any). There is even a [man]get_browser/man function that looks at that value and compares it to a browscap.ini file to give you various info about the (claimed) browser info.