The Demonweb is a microverse (infinite on the inside) and is the realm of the drow goddess Lolth. Her forces invade worlds and weave them into the Demonweb. Such worlds are accessible via portals within the microverse. It is a zero-gravity space of gray mist with web-tunnels in all directions. These tunnels (in which normal gravity exists) form an infinite labyrinth that extends into Lolth's personal realm, the Demonweb Pits. The Pits are the same as the Demonweb proper, but the mist outside the tunnels is black and can suck out a victim's soul. Since it is part of a microverse group called the Abyss, inhabited by demons (not to be confused with Hellgate's demons or the Daemons), Lolth finds it beneficial to keep up good or neutral relations with that realm's lords, although they are less personally powerful.
The Demonweb is filled with drow, spiders and spider-related monsters, and demons. The spiders are often normal, but some fiendish varieties are the size of elephants. Lolth's favorite demons are bebiliths (huge spider demons with scythelike claws that eat other demons) and yochlols (Lolth's handmaidens, shapeshifting demons that look like pillars of melting yellow wax with one huge red eye). The latter demons lead invasions and govern worlds for their goddess.