Spiders that use silk in one way or another to capture prey. In some families a web is constructed as a trap to catch prey, while in others silk threads are only used as signal trip-lines to warn the spider if prey is in close vicinity of the retreat.

The use of a web to capture prey is assumed to have developed long after spiders came into existence, and it took more than 200 million years for the first orb-web to appear.

The great diversity in web types suggests that this strategy is very successful. The webs of spiders are highly specialized structures that might be considered an extension of the spider's tactile sense organs.

A great variety of webs are made. Some may seem a chaotic arrangement of silk threads but most threads serve a definite purpose.