The region of a collider where the two particle beams collide is one of the most complicated parts of any high-energy physics accelerator. Each machine has different requirements for the design of this interaction region (IR) and yet, there are also many similarities or common constraints between IR designs. In addition, there are usually conflicting requirements from the elements of the accelerator and the detector components both of which share the space around a collision point. This almost always generates a severely over-constrained problem that invariably requires compromises from both the accelerator design and from the detector design. I will discuss the similarities and differences between various accelerator designs and describe the methods or techniques I use for generating designs of interaction regions.