<Li> The portion of a storage medium, such as a track or band, that is accessible to a given reading or writing station or head . </Li> <Li> A buffer from which messages can be' put' and' got' . See Actor model and process calculi for discussion on the use of channels . </Li> <Li> In a communications system, the physical or logical link that connects a data source to a data sink . </Li> <Li> A specific radio frequency, pair or band of frequencies, usually named with a letter, number, or codeword, and often allocated by international agreement . Examples: <Ul> <Li> Marine VHF radio uses some 88 channels in the VHF band for two - way FM voice communication . Channel 16, for example, is 156.800 MHz . In the US, seven additional channels, WX1 - WX7, are allocated for weather broadcasts . </Li> <Li> Television channels such as North American TV Channel 2 = 55.25 MHz, Channel 13 = 211.25 MHz . Each channel is 6 MHz wide . Besides these "physical channels", television also has "virtual channels". </Li> <Li> Wi - Fi consists of unlicensed channels 1 - 13 from 2412 MHz to 2484 MHz in 5 MHz steps . </Li> <Li> The radio channel between an amateur radio repeater and a ham uses two frequencies often 600 kHz (0.6 MHz) apart . For example, a repeater that transmits on 146.94 MHz typically listens for a ham transmitting on 146.34 MHz . </Li> </Ul> </Li>

Why is it important to limit the length of a message sent over a communications channel