Information, Computer and Network Security Terms Glossary and
A collision occurs when multiple systems transmit simultaneously on the same wire. An Ethernet network uses Carrier Sense Multiple Access/Collision Detect (CSMA/CD) to allow devices to take turns using the signal carrier line. When a device wants to transmit, it checks the signal level of the line to determine whether someone else is already using it. If a line is in use, the device waits and retries. If the line is not in use, the device transmits.