Network topology is the layout pattern of interconnections of the various elements (links

Data link

In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...

, nodes

Node (networking)

In communication networks, a node is a connection point, either a redistribution point or a communication endpoint . The definition of a node depends on the network and protocol layer referred to...

, etc.) of a computer

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

 or biological network.
Network topologies may be physical or logical. Physical topology

Topology

Topology is a major area of mathematics concerned with properties that are preserved under continuous deformations of objects, such as deformations that involve stretching, but no tearing or gluing...

 refers to the physical design of a network including the devices, location and cable installation. Logical topology

Logical topology

Logical topology is a network computing term used to describe the arrangement of devices on a network and how they communicate with one another....

 refers to how data is actually transferred in a network as opposed to its physical design. In general physical topology relates to a core network whereas logical topology relates to basic network.

Topology can be understood as the shape or structure of a network.