Connections are the lines between manifests in the Massdriver UI. They indicate other application and infrastructure bundles that a bundle is dependent on. They can be thought of as an "input" that is another package's artifact.
Connections are unidirectional. They always flow from "left" to "right" and are the edges of a directed acyclic graph defining the dependency hierarchy of your infrastructure and applications.
A dotted line indicates that an artifact has not been provisioned yet for the connection.
A solid line indicates that an artifact has been provisioned for the connection.