The mapping and measuring of relationships and flows among people, groups, organizations, computers, Web sites, and other actors is called social network analysis (SNA), which we will discuss in greater detail later in the chapter. Each connection, or relationship, between actors is known as a network tie, while each actor, or point on the network, is referred to as a node. In the previous figure, Thomas is a node and his connections to Albert, Eric, Martha, and others are network ties. Direct ties are those in which a single link spans two actors; indirect ties are where connections exist between actors, but only through other actors (hence, indirect ties). You can see that Thomas has four direct ties and is indirectly tied to everyone in the network. Conceptually, you probably have indirect ties to everyone on the planet but that does not necessarily mean they come to mind as part of your social network.