The Sega Master System is a video game console made in 1986. It was not very popular in North America and Japan but was very popular in Brazil. One of the most popular game of the Sega Master System was Sonic the Hedgehog.
The Sega Game Gear is a handheld video game system which was based on the technology found in the Master System. It was released in Japan in 1990, and then released later in Europe, the United States and Australia.