Used in networking and telecommunications, a patch panel is pretty much a junction box. All communications wall cable should be punched down to a patch panel, with jumper wires connecting the circuit to its final destination (say, your server).

Why use a patch panel? Well, apart from it being the professional thing to do, the cable at the end of a run is typically the cable that breaks first. When (not if) the end of your cable circuit breaks due to physical back-and-forth, it is easily replaced -- if you've used a patch panel and jumpers. If you haven't, you'll have to figure out where it's broken, then punch down another length of cable. Troubleshooting where a cable is broken requires a time domain reflectometer, and it's a pain in the ass. If you're using fiber, the OTDR required is highly expensive. It's just better to use a patch panel in the first place. The cables punched down to the patch panel don't move, so they don't break nearly as often.