Microsoft has big plans for the Xbox One, and those plans require a gigantic infrastructure. Xbox Live for Xbox One will be supported by more than 300,000 dedicated servers. According to Microsoft, that's more computing power than all computers in existence in 1999.
When Xbox Live launched it, it used 500 servers. It grew to 15,000 servers with the Xbox 360. Xbox One will use 20 times this amount.
All of these servers will be used for things like cloud saves, gameplay video storage, and dynamic achievement data. Xbox One will also feature a native video editing program.