I was thinking on what all a website can do to track or collect various data from the computers or cellphone these days. This is because I learnt that cookies can track other tabs on the same browser. If that's the case, in comparison to various applications available on handheld devices, what all can a standalone website do to collect data from the user?

The data might be both browser data or files in the computer/handheld. Basically, I'm asking what kind of information can the presently advanced websites or servers collect using scripting and stuffs.