A Hive is the nesting ground of a Queen Xenomorph. Potential hosts are brought into the hive to be cocooned in hive webbing by Drones , awaiting implantation with Chestburster embryos by Facehuggers hatched from the Queen's eggs.
Secreted by Xenomorphs, the web-like substance dubbed as "hive webbing" eventually hardens into a strong, resinous material used to trap potential hosts for implantation and birth. Quickly overwhelming an area, hive webbing forms the basic structure of the hive. Warrior Xenomorphs ambush enemy invaders from their resting places within, blending in seamlessly into the walls and ceilings. The structure of a Hive also appears to have a disrupting effect on motion tracker operation, generating a host of false readings that imply the entire area is awash with sporadic movement, making genuine readings harder to spot. The exact cause of this is unclear.
The hive itself takes the form of a warren-like maze of tunnels spreading outwards from a central Egg chamber, where the Queen will reside. It should be noted that while a Queen is typically found overseeing a Hive, one is not necessarily required for a Hive to form. Indeed, construction of a Hive may be a precursor to Queen development in many cases. In this respect, a Xenomorph Hive shares similarities in its architecture with both spider webs and wasp nests, while being directly comparable to neither. Should the Hive is constructed within existing non-Xenomorph structures (ex. Hadley's Hope), the webbing helps to disguise existing visual cues in the environment, turning the area into a disorientating maze and making escape from and/or assaults on the Hive highly difficult.
The atmosphere within a Hive is typically very warm. A Queen will often locate her Hive in an area where these properties are already apparent, such as large industrial facilities where there is an abundance of ambient heat. It is also possible the Hive structure, or perhaps the resident Xenomorphs themselves, somehow raise atmospheric temperatures within the Hive to meet this requirement.