There are several types of layers present in network protocols and the OSI (Open Systems Interconnection) model. Each layer has its own specific function and contributes to the overall communication process. Let's discuss these layers in detail:

**1. Physical Layer:**
The Physical layer is responsible for the actual transmission and reception of raw data bits over a physical medium. It deals with electrical, mechanical, and functional specifications, such as cables, connectors, and network interface cards (NICs).

**2. Data Link Layer:**
The Data Link layer provides error-free transmission of data frames between adjacent network nodes. It is responsible for framing, error detection, and flow control. It also defines protocols for accessing the physical medium, such as Ethernet.

**3. Network Layer:**
The Network layer is responsible for addressing, routing, and controlling the flow of data packets between different networks. It ensures that data reaches its destination by selecting the best path and handling logical addressing using IP (Internet Protocol).

**4. Transport Layer:**
The Transport layer ensures reliable and efficient end-to-end delivery of data. It breaks the data into smaller segments, adds sequence numbers, and provides error recovery mechanisms. It uses protocols like TCP (Transmission Control Protocol) or UDP (User Datagram Protocol).

**5. Session Layer:**
The Session layer establishes, manages, and terminates communication sessions between applications. It provides services like session establishment, synchronization, and checkpointing. It ensures that multiple connections can be organized into sessions.

**6. Presentation Layer:**
The Presentation layer is responsible for data representation and conversion. It handles the formatting, compression, and encryption of data to be sent across the network. It ensures that data is in a usable format for the application layer.

**7. Application Layer:**
The Application layer provides services directly to the end-user applications. It enables user interaction with the network and supports various protocols for tasks like file transfer, email, web browsing, etc.

These layers are defined in the OSI model, which is a conceptual framework that standardizes the functions of each layer in a network communication system. The model helps ensure interoperability between different vendors and allows for modular design and troubleshooting.

In summary, the different layers in network protocols and the OSI model play specific roles in the communication process. They handle tasks like physical transmission, error detection, routing, reliable delivery, session management, data formatting, and user interaction. Understanding these layers is crucial for designing, implementing, and troubleshooting network systems.