Okay don't listen to those idiots.
First, renderstep is a roblox only event.
It happens every time your computer refreshes the screen, which is about 60 times a second, however other peoples are different.
You may have seen a service called "RunService" in some scripts. If you don't know what a service is, think of it as similar to Teams or ServerScriptService, or ServerStorage...everything you see in your Explorer window in studio is a Roblox Service. For example, they can be referenced as game.ServerStorage or game:GetService("ServerStorage").
RunService is a service that handles things related to a player's movement.
http://wiki.roblox.com/index.php?title=API:Class/RunService
RenderStepped ( double step )
Fires every render frame, which is approximately 1/60th of a second. step is the amount of time that elapsed between the last render step and this render step.
RenderStepped is an Event of RunService. Step is apparently a parameter of renderstepped. So if you were to type out the following:
game:GetService("RunService").RenderStepped:connect(function()
print('hi')
end)
It would print 'hi' about every 1/60th of a second. So don't run that code c: But I hope I helped you understand what RenderStepped does. I can't quite think of an example of applicable uses (except for the camera script I used it in earlier to remove jitter and make the camera 'move smoother') but I'm sure someone else can.