At a very basic level, networks are made up of nodes and links.

Nodes are the network participants: consumers, devices, customers, buyers, sellers, brokers, etc. Different types of nodes can have very different roles within the same network.

Nodes within the same network can differ in terms of their levels of impact, influence, power, and value. Central nodes are the nodes in a network with a high number of links and are often more valuable. Marginal nodes have relatively few links and typically have less value - although there can be exceptions if marginal nodes are connected to a few powerful nodes themselves. Accurately calculating the value of a node varies greatly from network to network.

Finally, network size can be measured by the total number of nodes in a network. The size of a network alone doesn't determine value, because the amount of activity in a network can vary.

Links are the connections between nodes or groups of nodes in a network. Not all links between the nodes in a network are equal. Links can vary (see below) in terms of directionality.

Links vary in terms of strength, which is a function of the durability, closeness, and activity between two nodes. For instance, your Facebook Messenger link to your best friend is a lot stronger than your link to someone who you haven't talked to since high school, but they both count as links in the Facebook Messenger network.