In plain English, a frame is a data packet or a data unit. Technically, a frame is a protocol data unit or PDU at the data link layer of the OSI model. The PDU at the different layer of the OSI model is named differently.
At the transport layer, for example, the PDU is called a TCP segment or a UDP datagram. Most applications use TCP, and thus a segment is often used to represent the PDU at this layer. At the network layer, the PDU is called a packet, or an IP packet. At the data link layer, the PDU is called a frame.
Different TCP/IP technologies use different frames in terms of the header information, and the maximum transmission unit of the data, or the payload capability.
An Ethernet frame has seven main parts: preamble, recipient MAC address, sender MAC address, type,data, pad, and FCS.

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