Search engine optimization began in the early 1990s with the development of the first search engines like Archie and Gopher. In the mid-1990s, the first search engine robots were created and Lycos, Yahoo, and Galaxy popularized the concept of search engines. Some companies began experimenting with search engine optimization in 1994 by focusing on submission processes, and the first spamming of search engines occurred shortly after. This led to an ongoing "cat and mouse" game between optimizers and search engines to manipulate or prevent manipulation of algorithm and results.