What does "sustained wind" versus "wind gusts" mean?

Sustained wind is the average wind speed over about 10 minutes — what you feel most of the time. Wind gusts are brief, stronger spikes that last only seconds. A forecast of "sustained 12 mph, gusts to 25" means the wind is generally blowing 12 mph, but it occasionally ramps up to 25 mph then drops back down. For cycling or running, sustained wind matters most. For events, tents, or structures, gusts are more important because brief strong winds can topple or damage things even if average wind is mild.