Are captures compulsory in checkers?

In most standard rulesets, yes. If a jump is available you must take it, which is why sacrificing a piece to force a particular capture is such a common tactic.

What can a king do that a normal piece cannot?

A king moves and captures diagonally both forward and backward, which roughly doubles its usefulness and is why crowning is a central goal.

How do you win a game of checkers?

By capturing all of your opponent's pieces, or by leaving them with no legal move available on their turn.

Checkers

You are red. Capture all AI pieces to win.

Your Turn

Checkers, also called draughts, is played on the dark squares of an eight-by-eight board. Pieces move diagonally forward, capture by jumping, and become kings when they reach the far side.

The rules fit in a paragraph, but the game rewards thinking several exchanges ahead, because captures are compulsory in most rulesets and can be chained into long sequences.

How to play

Move a piece one square diagonally forward onto an empty dark square.
Capture by jumping over an adjacent opposing piece into the empty square beyond it, removing the jumped piece.
If another jump is available from the landing square, continue jumping in the same turn.
Reach the opposite end of the board to be crowned king, after which the piece may move and capture backwards as well.
You win by capturing every opposing piece or leaving your opponent with no legal move.

Ideas that improve your play

Keep your back row intact early. Those pieces prevent your opponent from crowning kings and are hard to replace once advanced.
Advance in connected groups. A lone piece pushed forward is usually just an offer, because it can be jumped without reply.
Count exchanges before you commit. Offering a piece is often correct if it forces a jump that opens a longer capture for you.
Control the centre. Pieces in the middle have more diagonals available, while those against the side wall have their options halved.
Aim to crown kings, then use them aggressively. Their ability to move backwards makes them worth roughly two ordinary pieces.

Frequently asked questions

Are captures compulsory in checkers?: In most standard rulesets, yes. If a jump is available you must take it, which is why sacrificing a piece to force a particular capture is such a common tactic.
What can a king do that a normal piece cannot?: A king moves and captures diagonally both forward and backward, which roughly doubles its usefulness and is why crowning is a central goal.
How do you win a game of checkers?: By capturing all of your opponent's pieces, or by leaving them with no legal move available on their turn.