A glider (or featherweight spaceship) is the smallest, most common, and first-discovered spaceship. Its name is due in part to the fact that it is glide symmetric. It travels diagonally across the Life grid at a speed of c/4 and is often produced by randomly-generated starting patterns. Gliders are important because they are easily produced (see Gosper glider gun), can be collided with each other to form more complicated objects (see glider synthesis), and can be used to transmit information over long distances.
The glider was found by Richard K. Guy in 1970 while Conway's group was attempting to track the evolution of the R-pentomino. It is often stated that John Conway himself discovered the glider, but he has said that it was Guy.