I want to create a site in php such that, when user would login to my website, then they can add their favorite website and enter its login information once. My site will save his login information for other sites in my database, and the next time, user logged onto my website need not to enter his login information to other sides again. My site will automatically do this for them.
I am not sure whether this is possible or not. As I am a beginner in php. Also would javascript be useful for this?
Would it be possible to do this by limiting this feature to some fixed websites?
Ankur
Assuming that the sites are arbitrary third parties, then this is impossible (and if it were not then users using your service would probably be violating the terms and conditions of most of the sites they used you to access by sharing their passwords).
If you control the sites, then the key-phrase to search for is single sign on
If the sites are ones that buy into using third party authentication then you want to be an OpenID Provider (stackoverflow is an OpenID Consumer, which is why you can log in by using (for instance) your Flickr photo page URL).