A combination of predecessor and successor tasks linked together in a logical sequence by means of precedence.'

SOURCE; microsoft project

1. Graphical representation of activities or nodes and the dependencies between them. 2. 'The logical order of tasks that defines the sequence of work in a project. Networks are usually drawn from left to right, with lines drawn between to indicate the precedence between tasks. Arrow heads are often placed on the lines to indicate the direction of the flow through time.