In an integration network, vital relations are the connectors that serve to identify counterparts within and across mental spaces. Gilles Fauconnier and Mark Turner argue that there is a relatively small set of vital relations which recur frequently in conceptual integration. It is precisely the frequency with which these connectors occur that licences the application of the term 'vital' to describe them.

The importance of vital relations is that conceptual integration proceeds by virtue of compression of a given vital relation holding between counterparts in distinct input spaces, resulting in a compressed vital relation which is projected to the blended space. A vital relation which connects counterparts across input spaces is known as an outer-space relation. The compressed vital relation that occurs in the blended space is known as an inner-space relation. Table 12 provides some examples of outer-space vital relations and their compression into inner-space vital relations.