A plug is a part with some type of projection that goes into a port. A port is a part that has some type of matching hole or slot that accepts the plug. You never put a port into a plug; it’s always the other way around. The term jack is used as an alternative to port, so you may also put a plug into a jack. The term connector describes either a port or a plug. (See Figure 2-12.) As you progress through this chapter and see the different plugs and ports, this will become clearer.