Layer III refers to the network layer in the OSI (Open Systems Interconnection) model, which is responsible for routing data packets between devices across different networks. It manages the addressing and forwarding of data, ensuring that information reaches its intended destination. Common protocols associated with Layer III include IP (Internet Protocol) and ICMP (Internet Control Message Protocol). At this layer, devices such as routers play a crucial role in determining the best path for data transmission. Layer III also handles packet fragmentation and reassembly, allowing data to be sent efficiently over various types of networks. This layer is essential for enabling communication between different network segments.