There are dozens of knots that might be worth learning as a climber. But for the most part, you can get up and down any climb on Earth with just these sevan basic knots, including the Girth Hitch, the Munter Hitch, and the Double Fisherman's Knot.
Welp, I can feel the time management thing setting in already. (Just spent several hours watching climbing videos instead of working on my thesis. x_x) Also, that last bit could mean so many things, good and bad.