Once you start riding, you’ll notice that other riders on motorcycles will wave or make a gesture (peace sign, thumbs up, etc) of some sort as you pass by each other. Why? It’s just a friendly way to say you are a member of a select group of adventurers: a motorcycle rider. So wave back. This phenomenon is mostly restricted to North America, though Brits use something much more subtle: “the nod”, In other parts of the world, or near riding rallies, riding motorcycles is as common (or more so) than driving cars, so they don’t tend to wave or they’d be doing it all the time.