The smallest, most common and first
discovered spaceship. This was found by Richard Guy in 1970 while
Conway's group was attempting to track the evolution of the
R-pentomino. The name is due in part to the fact that it is
glide symmetric. (It is often stated that Conway discovered the
glider, but he himself has said it was Guy. See also the cryptic
reference ("some guy") in Winning Ways.)

The term "glider" is also occasionally (mis)used to mean "spaceship".

Game of Life Explanation

The Game of Life is not your typical computer game. It is a cellular
automaton, and was invented by Cambridge mathematician John Conway.

This game became widely known when it was mentioned in an article
published by Scientific American in 1970. It consists of a grid of
cells which, based on a few mathematical rules, can live, die or
multiply. Depending on the initial conditions, the cells form various
patterns throughout the course of the game.

Rules

For a space that is populated:

Examples

Each cell with one or no neighbors dies, as if by solitude.

Each cell with four or more neighbors dies, as if by
overpopulation.