Track events (classified by distance in metres):
100m, 200m and 400m: Sprint races where the athletes run as fast as they can in their own lane for the entire distance.
800m and 1500m: Middle distance events where athletes can't maintain top speed, so tactics come into play. Athletes are also permitted to run out of lane.
5000m and 10,000m: Long distance events run out of lane, where endurance is vital, in addition to tactics.
110m hurdles (100m for women) and 400m hurdles: Sprint races where the athletes also have to jump over 10 barriers equally spaced down the track. The men have higher hurdles and a slightly longer distance to cover in the shorter event.
3000m steeplechase: An endurance race over hurdles. After an obstacle-free first lap, the competitors tackle five hurdles, including a water-jump, on each successive lap. This is a men's event only at Doha 2006.
4x100m and 4x400m relays: Team sprint races where four athletes race in sequence, passing a baton to the next runner. Dropping the baton results in disqualification. The first team whose final athlete crosses the line with the baton is the winner.
Competitors aim to jump the highest over a bar. They have three chances to clear the bar. If they clear it, then the bar is raised gradually until only the winner remains.
Similar to the high jump, but competitors are allowed to use a long pole to help propel them over the bar and can therefore clear great heights.
Competitors aim to jump the furthest. They have three chances to run and jump from behind a line into a sandpit.
Similar to the long jump, but competitors have to take a hop, a skip and a jump at the end of their run up.
Competitors throw a long spear, known as the javelin, as far as possible from behind a line. The javelin must stick into the ground on landing to count.
Competitors throw a heavy metal sphere, known as a shot, as far as possible, using a strictly controlled pushing motion from the shoulder.
Competitors throw a disc as far as possible using a straight arm and a swinging action.
Competitors throw a metal sphere on a chain, known as a hammer, as far as possible using a swinging action.
A long endurance road race, run over the traditional marathon distance of about 42 kilometres (26.2 miles).
20km race walk:
An endurance road race conducted under strict walking rules; competitors must keep one foot on the ground at all times to prevent running
A men's event featuring 10 disciplines. On day one, competitors start with the 100m, followed by the long jump, shot put, high jump and 400m. Day two features the 100m hurdles, discus, pole vault, javelin and the final event, the 1500m. Scoring tables are used to give a final points total.
A women's event featuring seven disciplines. On day one, competitors start with the 100m hurdles, followed by the high jump, shot put and 200m. Day two features the long jump, javelin and 800m. Scoring tables are used to give a final points total.