Bends: Bends are knots that tie two ropes together.
Examples: Square Knot, Surgeons Knot, Sheet Bend, Double Fisherman Knot, Reef Knot
Loop Knot: Loop Knots are more uncommon than the other knots, loop knots are basically loops at the end of a string. Some Loop Knots tighten when they are pulled, and others stay the same no matter how hard you pull.
Examples: Slip Knot, Bowling Knot, The "Bow" Knot (You tie your shoes with it), Honda/Lasso Knot
Hitches: Hitches are used to tie a rope to another object.
Examples: Half Hitch, DOUBLE Half Hitch (all the way across the sky), Clove Hitch, Constrictor Knot,
Stopper Knots: Yea, I know I said that there are three main types of knots, and technically their are! However, some knots fall into a category called stopper knots. There are only three or five types of stopper knots, and thats why its not technically a category. Stopper knots are used to stop rope from going through a hole.
Examples: Figure Eight Knot (Thats about it)
The Best Knots: This is a highly debated question in the world of knotted, but overall, these are considered your need to know knots.
The Bowline: This knot is the most useful loop knot. It can support hundreds of pounds without slipping. Personally, I would use it to support me while hanging off a cliff.
The Sheet Bend: Forget about the Square Knot, this is undoubtedly the best way to tie two ropes together! Make sure you learn this one!
The Clove Hitch: Secure and stong, but easy to untie. Ive seen people tie Clove hitches in five seconds using only one hand!
The Worst Knot: This is also a debated topic, but I think that the square knot is the worst knot. Its used all the time, and it is one of the loosest knots. I would suggest forgetting about the square knot and instead switch to the Sheet Bend, its a much better knot.
Well, that all I have for you, have fun knotting guys!