It comprises the nodes, writeups, and nodeshells shaped by users and as yet unshaped freegel. It is the medium in which godusergroup and editorusergroup entities dwell and swim to care for, cool, and cull nodes.
The secondary purpose of nodegel is to be formed into nodes. The primary purpose of nodegel is ineffable.
It is said that the nodes and writeups describe a world outside of the gel. This is purely speculative, of course. This is as unlikely (but as intriguing) as the term "users" referring to anything other than processes of noding.
To deal briefly with this, that there is some indication that there is something other than the nodegel can be arrived at by a process of observation. The slurry of freegel that appears at the "edges" of the nodegel is thought to indicate the presence of vents. The pattern of the emission has long repeating slashes or bars. That this indicates an actual "vent" of some substance other than the gel itself is however unprovable. In fact, it seems that this phenomenon is only observable with the dorsal eyestalks of godusergroup entities when all nineteen stalks are aligned and blinking rapidly. The visual units of the vestigial heads of editorusergroup entities seem unable to detect this. And so this too, while interesting, is only speculation. After all, the gradual dissolving of the editorusergroup entities' heads is itself explained in the documentation as merely the slow dissolution of the illusion of being a user and the gradual dawning of enlightenment as the gel itself. However, even godusergroup entities, while headless, are themselves often caught in habits of thought that they were once something other than the gel swimming in the gel.
This is getting scary to think about. Forget I mentioned it.