The Xbox was Microsoft first home video game console they brought into the gaming console market. The Xbox was competing against the Playstation 2, the Sega Dreamcast and the Nintendo Gamecube and was very successful, having great launch titles, PC-like architecture, and more raw power than any of it's sixth-generation brethren
The Xbox 360 is a home video game console developed by Microsoft. It is the successor of the Xbox and the predecessor of the Xbox One. The Xbox 360 was developed to compete with Sony's Playstation 3 and the Nintendo Wii. The Xbox 360 was officially unveiled on May 12, 2005, with more details reveled a month later at E3.
Xbox One is a video game console developed and marketed by Microsoft. It was announced on May 21, 2013 and is the successor to the Xbox 360 and is the third console to join the Xbox family. The Xbox One was released across North America, several European markets, Australia, and New Zealand on November 22, 2013.