What is a data frame?

A data frame, also called a frame, is an organized structure into which data is placed for transmission across a network. The data frame defines how the data is organized (i.e., the relative position and length of fields and the type and placement of control information)

In serial communications, data is sent in streams one bit at a time. The data frame breaks the stream up into discrete chunks so that it can be better managed. If there is an error in transmission, only the affected frames need to be resent, not the entire transmission.

The structure of a data frame depends on the type of network. The original Ethernet data frame is shown below:

Note that the original Ethernet frame is slightly different than the IEEE 802.3 standard. In fact there are at least four different types of "Ethernet" frames in use today.