A planer is used to cut a (thin) layer off of your wood. This planes your wood, hence the name.
Planers come in different variants. The main ones are:
There are many different hand planes, and many different types of them. So many that you can collect them if you like, as show in this youtube video 🙂
The most recognizable plane is one like this:
(Electrical) hand planer
Note the r at the end there. The planer is the electrical variant. These ones are faster but you won’t have the satisfaction of the manual labour you have with the hand plane. But depending on the job, this is your go-to tool.
Here’s an image of a hand planer:
Please don’t buy the cheapest one, or you’ll end up with a crappy one like I have where the blade isn’t horizontal, and there’s no way to align it 🙁 So now I have a piece of scrap that I can throw away. So, check yours out closely before you buy it, or check out the reviews!
The one in the picture is actually a decent one!
Benchtop planer / Thickness planer
This is the tool where you feed your wood in from one side, and it comes out planed on the other side. Totally nifty tool!
What also helps is that the top and bottom will be parallel when your wood comes out!