Carrier-sense multiple access with collision detection (CSMA/CD) is a Media Access Control (MAC) method used most notably in early Ethernet technology for local area networking . It uses carrier-sensing to defer transmission until no other stations are transmitting. This is used in combination with collision detection in which a transmitting station detects collisions by sensing transmissions from other stations while it is transmitting a Frame . When this collision condition is detected, the station stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame.

Source: https://en.wikipedia.org/wiki/Carrier-sense_multiple_access_with_collision_detection

• CSMA/CD: carrier sense multiple access/collision detection
• Used to determine which NIC should use a shared cable at a given moment
• NICs listen and if the line is free can send a frame
• Equal access
• If a collision occurs NICs will calculate a random interval and attempt to resend.