How can a bill become a law if the President doesn't sign it? How can a bill be vetoed if the President doesn't physically veto it?

1.) presidential signature - A proposed law passed by Congress must be presented to the president, who then has 10 days to approve or disapprove it. Normally, bills he neither signs nor vetoes within 10 days become law without his signature. ...

2.) Congress can override the veto by a two thirds vote of both chambers, whereupon the bill becomes a law. If Congress presents this during the 10 day period and president does not sign the bill a pocket veto occurs and the bill does not become law