What happens on each move?
All tiles slide as far as possible in the chosen direction. Two equal tiles that meet combine into one tile with double the value. A tile merges only once per move, and a new tile appears after a move changes the board.
2048.
Slide the whole board. Equal numbers meet, double, and make room for the next move.
A little more about 2048.
Can I keep playing after 2048?
Yes. Reaching 2048 is a milestone, not a forced stop. Continue making larger tiles until no legal move remains, or start a fresh board whenever you want.