What is the correct flag technique?

From the IFAB practical guidelines (2026/27):

• Keep the flag unfurled and visible to the referee at all times, usually in the hand closest to the referee.
• To signal: stop running, face the field, make eye contact with the referee, and raise the flag with a deliberate motion (not hasty or exaggerated). The flag should be like an extension of your arm.
• Raise the flag with the hand you'll use for the next part of the signal. If you need to change hands, switch the flag below the waist.
• If you signal that the ball is out of play, hold the signal until the referee acknowledges it.
• Beep flags, where used, are only to get the referee's attention (for example offside, offences out of the referee's view, or tight out-of-play or goal decisions).
• Avoid obvious hand gestures. A discreet hand signal agreed in the pre-match discussion can help.