Quake has a very open game architecture. It lets you change almost anything in the game. Monsters, levels, sounds, even the game rules programmed into the game can be changed.
Monsters are animated 3D polygon models that have a skin stretched onto them. qME allows you to edit existing monsters or create new monsters from scratch.
qME is a one step solution to building Quake monsters. You will be able to do every aspect of building a Quake model; modeling, skin painting and animation are all supported.
When you create models in qME, you usually start by inserting objects from a library of prefab objects into your model, then paint skins and create animation sequences. When saving the model, all information needed by Quake is calculated and stored in your model file. The file that is created by qME are read directly by Quake.
If you want to create a model outside qME this is possible too. qME supports the most important 3D file formats, allowing you to import from most 3D editors. It also supports the import of skins from the clipboard or from a file so you can edit the skin in an external editor too.