The blue flagRace tracks have long used flags as a way for marshals to communicate with drivers. The colour and meaning of... There's more... is shown to backmarkersBackmarker is the name given to the drivers at the rear of the field when they are about to be... There's more... advising them to let the lead cars go past.
If a car is being lapped they are not considered to be racing against the cars coming through and therefore they need to let them through without impedingImpeding in F1 is typically seen during practice and qualifying, as all drivers are generally pushing during the race. In... There's more... them.
During Free PracticeFree Practice consists of three sessions (FP1, FP2 & FP3) held prior to qualifying. It is referred to as 'free... There's more... or QualifyingQualifying (Quali) is a one-hour session used to determine pole position and the order the cars will line up behind... There's more..., the blue flag is shown to a car that may hinder another car on a fast lap.
Ignoring this flag more than three times can result ina penalty.