Classification — where it appears
Also named here as semi rigid — the same set of essays touches all of them, so they are one junction rather than several.
Neither pinned nor rigid, which is every real connection
Frame analysis offers two options for a joint and reality supplies a continuum between them. Worse, the boundaries are not properties of the connection at all — the same end plate is rigid on a short stiff beam and semi-rigid on a long slender one.
The redistribution nobody chose
A beam designed as simply supported, on connections that are not pins, has end moments the analysis never predicted and a mid-span moment smaller than it was sized for. Usually that is safe. It is never intentional, and there is one direction in which it is not safe at all.
Named alongside it
The objects these essays reach for when they reach for this one.
ConnectionJoint stiffnessMoment redistributionSemi rigidBeam columnDeflectionFlexural rigidityMoment rotationRotational springServiceability