A node in a computer network is a device that is connected to other devices within the same computer network. It can be a computer, a server, a switch, a hub, a router, or any other device that has an IP address and can communicate with other devices over a network.

The term node is often used interchangeably with host, endpoint, or computer, but it can also refer to more complex devices that act as intermediaries in the network communication. These devices, such as switches and routers, are known as network nodes and play a critical role in the functioning of the network.

A node can perform various functions within a network, including sending and receiving data, transmitting messages, executing applications, and providing resources to other nodes in the network. Each node is assigned a unique IP address that identifies it on the network, allowing it to be located by other nodes when required.

Network nodes can be connected in different ways, depending on the topology of the network. A topology describes the physical or logical layout of nodes and their interconnections. Common network topologies include star, bus, ring, mesh, and hybrid.

In a star topology, nodes are connected to a central hub or switch, which acts as a central point of control for the network. In a bus topology, nodes are linked together along a single communication line. In a ring topology, nodes are linked in a circular fashion, with each node communicating only with the nodes immediately adjacent to it.

A mesh topology consists of multiple nodes that are interconnected in a complex web-like structure, allowing data to be transmitted between multiple paths. Finally, a hybrid topology is a combination of two or more different topologies.

Each topology has its advantages and disadvantages, with some being more suitable for specific network requirements than others.

In summary, a node is a device that is connected to a computer network and can communicate with other devices in the network. It can be a computer, a router, a switch, or any other device that has an IP address. Network nodes have unique functions depending on the topology of the network and play a critical role in ensuring the smooth functioning of the network.