Network topology refers to the physical or logical layout of a computer network. It defines how devices are connected to each other and how data flows within the network. Here are some common network topologies:

1. Bus Topology: In a bus topology, all devices are connected to a central cable, known as the bus. Data is transmitted along the bus, and each device receives the data intended for it. However, if the bus cable fails, the entire network can be affected.

2. Star Topology: In a star topology, all devices are connected to a central device, such as a switch or hub. Each device has a separate connection to the central device. If one device or cable fails, only that particular connection is affected, and the rest of the network remains operational.

3. Ring Topology: In a ring topology, devices are connected in a closed loop or ring, where each device is connected to two neighboring devices. Data circulates around the ring in one direction, and each device processes the data as it passes through. If one device or cable fails, the entire network can be disrupted.

4. Mesh Topology: In a mesh topology, every device is connected to every other device in the network. This provides redundancy and multiple paths for data to travel, increasing fault tolerance and network reliability. Mesh topologies can be full mesh (direct connection between every device) or partial mesh (selected devices are directly connected).

5. Tree Topology: A tree topology, also known as a hierarchical topology, is a combination of bus and star topologies. Devices are arranged in a hierarchical structure, where lower-level devices connect to higher-level devices until they reach a central root node. This topology is commonly used in larger networks, such as organizational networks.

6. Hybrid Topology: A hybrid topology is a combination of two or more different topologies. For example, a network may have a combination of star and ring topologies to leverage the benefits of each topology.

The choice of network topology depends on factors such as the size of the network, the number of devices, the required bandwidth, fault tolerance requirements, and cost considerations. Each topology has its own advantages and disadvantages in terms of scalability, reliability, ease of installation, and network performance.