Tholian Web

The Enterprise attempted to retrieve the Captain, but was challenged by a Tholian vessel. After a brief stand-off the Tholian attacked the Starship and was disabled. Whilst the Enterprise continued rescue attempts, another Tholian vessel arrived. The two alien ships then began to create the Web.1

For two ships, the process of spinning the web is a long one. The vessels join briefly then begin to repeatedly circle the area to be sealed off, trailing between them an energy field filament. The filaments cross and re-cross, gradually enclosing the area in a gigantic cage like structure. Once complete, the web was strong enough to contain any attempt the ship might make to break out.1

Many aspects of the Web remain puzzling. At the very least it appears that it can only be used in a highly selective set of circumstances. In their first encounter the Enterprise was able to disable the Tholian vessel with only a few seconds of phaser fire, yet it took considerable time for the ships to create the web structure. If not for their attempts to rescue Captain Kirk, the Starship would certainly have been able to comfortably disable or destroy dozens of vessels in the time it took to create the web.1

Additionally, the web presents no real barrier to travel until it is largely complete - in the early stages, a ship could simply fly out of the web without trouble.1

However, when many Tholian ships come together they can forego the "spinning" process and simply project a web around an enemy ship in a matter of seconds. This makes the system much more useful in combat conditions. The Tholians of the Mirror universe used a web to ensnare the NX-01 in 2155, keeping it captive whilst they attacked and destroyed it.2