How does curling actually work?
Two teams slide stones down a sheet of ice toward a target, alternating shots, and score based on which stones end up closest to the centre. The tactical depth comes from the fact that stones already in play obstruct the ones still to come.
The basics. Each team of four delivers eight stones in total — two each — alternating with the opposition. A completed set of sixteen stones is an end, and a match consists of eight or ten ends.
Scoring. Only one team scores per end — the team with the stone closest to the centre of the house (the target rings). They score one point for each of their stones closer to the centre than the opposition's nearest stone. So a team can score up to eight, though anything above three is exceptional.
Stones outside the house do not score, regardless of position.
The hammer. The team delivering the last stone of an end has a substantial advantage, and this is the strategic centre of the game. Because of it, scoring only one point with the hammer is considered a poor outcome — you surrender the hammer for a single point. Teams with the hammer play aggressively to score multiple points; teams without it try to force a blank end (nobody scores, hammer retained) or to steal a point.
Sweeping. Brushing the ice ahead of the stone melts a microscopic layer of water, reducing friction. This makes the stone travel further and curl less. Sweepers therefore control distance and line in real time — they cannot speed a stone up, only reduce how much it slows.
Why stones curl. The stone is delivered with a slight rotation, and it gradually bends in the direction of that rotation. The precise physics has been genuinely debated and is more subtle than the simple friction explanation suggests.
Pebbled ice. The surface is deliberately sprayed with water droplets that freeze into small bumps, so the stone rides on their tips. Without pebble, the stone would not curl at all.
The skip directs strategy from the house and usually throws the final stones.