C-band (Comprise) is a portion of the microwave band ranging from 4-8 GHz, and a wavelength of around 5 cm. The C-band is commonly used for satellite communications.
The bands available for satellite communications are 3.4-4.2 GHz (space-to-Earth) and 5.925-6.725 GHz (Earth-to-space). More specifically, the bands 3.7-4.2 GHz (space-to-Earth) and 5.925-6.425 GHz (Earth-to-space) are usually referred to as "Standard" C-band and the bands 3.4-3.7 GHz (space-to-Earth) and 6.425-6.725 GHz (Earth-to-space) are usually referred to as "Extended" C-band.
The band is further used for radar, including weather radar, and Radio LAN in the 5 GHz range.