We've all seen the flags flown by track marshalls, but what do they all mean? Here's a quick rundown of the flags most commonly seen during a race :

Green flag - Means the track is all clear and riders may overtake.

Yellow flag - If being waved, it means danger immediately ahead. If stationary, it is used to reinforce the warning that caution is required ahead. Riders are not allowed to overtake while a yellow flag is being displayed. If a yellow flag is displayed at the starting grid of a race it means that the race start has been delayed.

Red flag - If stationary, it means the race or practice session is stopped, the track has been closed and all riders on the track are to return to pit lane slowly. If a stationary red flag is being shown at pit lane exit, riders may not exit pit lane.

Blue flag - If shown stationary, it means a rider is coming up behind. If being waved it means that a rider behind is about to overtake. In racing conditions it is shown to a lapped rider, the lapped rider must allow the following rider to overtake at the earliest opportunity.

Yellow & Red Striped flag - means there is oil or other substance which is making the track slippery, does not refer to rain.

White flag - means the riders are allowed to pit to change machines.

White flag, diagonal red cross - means 'drops' of rain are on the section of the track where it is shown.

White flag, diagonal red cross shown with Yellow & Red Striped flag - means rain on this section of track

Black flag - Shown in conjunction with a rider's number, it means that the rider must stop at the pits on the next lap and may not restart. The riders team must be notified prior to the flag being shown.

Black flag with orange disk - means the rider has a mechanical problem considered dangerous and must immediately leave the track.

Black & White Chequered flag - race or practice session is finished.