But sometimes those guesses go astray - especially when the gadget is completely new.
In 2005 and 2006, techies everywhere were trying to guess what Apple's newest gadget - the game-changing iPhone - was going to look like. Mostly, they were wrong!
Here are a few of the most interesting guesses, as found by Gizmodo.
This one runs with what phones looked like at the time. It attaches an iPod to a flip phone. Not even close!
This one is an interesting try. It looks like a next-generation iPod with a slide-out keyboard. Notice that a lot of the guesses included the iPod click wheel. Nobody seemed to be guessing it would be a touch screen.