[ColdOne]

You can put the tail number of any plane on that site and get flight info?

[grobdriver]

You can put the tail number of any plane on that site and get flight info?

Only if it's on an IFR flight plan.

[Signalman]

Correct, if it is flying an IFR (Instrument Flight Rules) tracked by ATC on radar, or VFR-flight tracking (flying under visual flight rules but you have asked ATC to track you on radar).