CSMA/CD stands for Carrier Sense Multiple Acccess / Collision Detection. CSMA/CD is a Media Access Control (MAC) protocol. It defines how network devices respond when two devices attempt to use a data channel simultaneously and encounter a data collision. It minimizes the number of collision but in specific process. The process is:
1. The device with a frame to send listen until ehternet is free,

2. If ethernet is free then it starts sending frame,

3. The sender listen to make sure no collision occur,

4. If there is a collision,then its sends all station a jaming signal to ensure that all station recignize the collision,

5. After jaming is completed each sender sends one by one the original collided frame, randomize a timer and wait that long before sending.

[Note: The jaming signal are done for those frames which are responsible for collision, other station do not have to wait.]