The Easter cactus (Schlumbergera gaertneri), or spring cactus, is named for the time of year that it typically blooms, which is in early spring right around the Easter holiday. It’s been reclassified several times, so you may find it referred to as Rhipsalidopsis gaertner or Hatiora gaertneri.

Though “cactus” is part of their name, they’re actually epiphytic succulents which are native to the tropical rainforests of Brazil. Instead of requiring soil to grow, they take in nutrients and moisture from the air and debris around them. Maybe that's why mine do the best when I somewhat neglect them... Easter cactus bloom sometime between March and May.