What is full duplex and half duplex in computer networking.

Actually Duplex means you are used to send and receive data from a single device.

Half-duplex devices let you send and receive, but only one-way at a time.
For example, walkie-talkie. You have to push the TALK button to send your message. But as long as you are holding the TALK key, you can't hear what anyone else is saying. You must release the button to receive.

Full duplex devices letting you to send and receive date simultaneously.
For example, Cell phone. You may send and receive data at the same time.

Both Half Duplex and Full Duplex are two way communicative devices but whats the difference is in Half Duplex, there is only 1 way at a time where as in Full Duplex, we use 2 ways at a time.