In a social network diagram people are represented by dots. These dots are called nodes. The color of the nodes are determined by attributes. The location of a node in the network is based on its connections to other nodes within the network. In general, someone with many connections is placed centrally, whereas someone with few or no connections is placed in the periphery.
Ties are the arrows between people in a social network diagram. Ties indicate relationships. If a tie is one way-directed it shows an unbalanced relationship where one person has indicated another as a relation, but is not indicated as such by the other. If, however, it is a two way-directed tie the relationship is balanced (these are also called reciprocal ties).
Clusters are isolated groups of people. They are characterized by being highly connected internally and only having a few connections to the remaining network.
A sociogram is a visualization of a network. Sociograms are also referred to as social network diagrams and social network graphs. Nodes and the ties between them constitute sociograms.
When clusters are not connected there is a structural hole between them. In other words, structural holes are the missing ties in the network.
Formal networks are the structured networks put in place by management. An organizational chart and a chain of command are both examples of formal networks. Teams formed by a manager could also be referred to as formal networks.
These are the networks most often studied with a social network analysis. An informal network is a social network established by the employees themselves and seldom deliberately. It can be both a professional network, say, for sharing best practices, and a more social-oriented network. The main characteristic is that the group is self-established. The saying “heard it on the grapevine” refers to such informal networks and describes how news spreads in an organization.