The similarities and differences between frontal zones and airstream boundaries are explored. Frontogenesis is used as a measure of the intensification of the horizontal temperature gradient (frontal zone), whereas a kinematic expression for the contraction rate of adjacent air parcels is a measure of the intensification rate of airstream boundaries. The strength of the thermal gradient associated with the frontal zone depends on the orientation of the developing airstream boundary and the associated axis of dilatation relative to the thermal gradient. Within this framework of frontal zones and airstream boundaries, we will examine different aspects of idealized and observed midlatitude cyclones (e.g., surface cold front, upper-level front, warm front, bent-back warm front, trowal, occluded front, etc.).