The name of the game is speed – it is the Indianapolis Motor Speedway, after all – but race officials give drivers other commands, too. And they're often communicated by flags.

Here's what each Indy 500 flag color means:

Green: Go! This signals it's time to start ... or restart ... practice, a qualifying attempt or the race.

Yellow: Caution; there's an issue on the track, so cars must proceed at less than full speed and there is no on-track passing. It often means there has been a crash, and safety equipment is on track to clean it up and attend to any injuries.

Red: This flag is the stop sign. All cars are ordered to the pits, often because of a serious accident that will require a lot of attention or weather that makes racing unsafe.

Blue with a diagonal yellow stripe: A driver must allow an oncoming car to pass. It's no fun getting lapped, but it's worse to hold up faster cars competing for position.

Black: Head to the pits and wait for further instructions. There's a significant issue that needs to be addressed. Black-flagged cars can be disqualified.

Black flag with white cross: A driver receiving this flag has been disqualified, and the car will no longer be scored.

Red and yellow striped flag: The track is slippery, likely from oil or water, and drivers must be aware.

White: This means there is one lap left in the qualifying attempt or race.

Checkered: The practice, qualifying attempt or race is done. The driver getting to this flag first during the race wins.

Why was there a red flag in the Indy 500?

There were three red flags in the final 15 laps of the 2023 Indy 500. The last of those red flags allowed a one-lap, green-flag shootout in which Josef Newgarden passed Marcus Ericsson and hung on to win.

Ericsson, the 2022 race winner, blasted that move.

“I don't think it's safe to go out of the pits on cold tires for a restart when half the field is sort of still trying to get out on track when we go green,” said Ericsson in the post-race press conference.

“I don't think it's a fair way to end the race. I don't think it's the right way to end the race.”

The first red flag came on Lap 186 when Felix Rosenqvist and Kyle Kirkwood made contact, sending one of Kirkwood's tires out of the track and into a parking lot. No one was injured.

Pato O'Ward crashed with 7 laps to go, bringing out another red flag.

This article originally appeared on Indianapolis Star: Indy 500 race flags: A guide to what the different colors mean at IMS