What is a protocol data unit (PDU) in the context of Ethernet?

In the context of Ethernet, a protocol data unit (PDU) refers to the unit of data that is defined and used within a specific protocol layer due to the structured nature of data transmission in networking. Each layer of the OSI (Open Systems Interconnection) model has its own PDU; for example, in Ethernet, the PDU is often referred to as a "frame." The concept of PDU is crucial, as it allows for standardized communication between devices across the network by establishing how data is encapsulated, transmitted, and interpreted at each layer of the network protocol stack. This encapsulation process includes various header and trailer components that facilitate error detection, addressing, and other necessary functions to ensure reliable communication. Therefore, recognizing the PDU as the basic unit of data for a particular protocol layer is essential for understanding how different networking protocols interact and operate within an Ethernet network.