Where can you download garrys mod demo

There currently is no demo to Garry's Mod. Or not one that I know of but if you were looking at getting Garry's mod I would suggest looking a videos of it first and if you want to buy it Garry's mod is a great game with a few different game modes including sandbox where you can build whatever you want to and multiplayer where there is a variety if different multiplayer games to have fun in so You should consider buying it if you are were looking to it is a good deal for 10 dollars.