There are over 100 different openings in chess, but you don't have to memorize them all. To have a good repertoire, you should probably know about 15-20 openings, and those should include both black and white. However, it's also really important to know a proper response to each of the openings. That way, if your opponent opens with e5, Sicilian, Ilya Kan, or French, you'll know what to do.