A method for detecting read, transmit, and write errors in data. At the
transmission end, the system treats a block of data as a single binary number,
divides it by some specified binary number, and appends the remainder (called
the CRC character) to the data. At the receiving end, the system recalculates the
remainder and compares the result to the CRC character. If the two agree, there
are no errors.

data channel

A communications path between two points used to transmit digital signals.

data-communications equipment (DCE)

The equipment (usually a modem, data module, or packet
assembler/disassembler) on the network side of a communications link that
makes the binary serial data from the source or transmitter compatible with the
communications channel.

datagram

In packet switching, a packet that carries information sufficient for routing from
the originating data terminal equipment (DTE) without the necessity of
establishing a connection between the DTEs and the network. Connectionless,
unreliable.

data link

The configuration of physical facilities enabling end terminals to communicate
directly with each other.