Someone once told me: If you’re going to be in a room within a short time its better to leave the light on rather than turn them off and then back on again when you come back in order to save electricity. True or false?

(may be broke/outdated!)
Someone once told me: If you’re going to be in a room within a short time its better to leave the light on rather than turn them off and then back on again when you come back in order to save electricity. True or false?