The answer to 'what is spider' is a spider is a type of arachnid, a class of invertebrate animals that have eight legs, two body parts, and no wings or antennae. Spiders are found all over the world and play an important role in many ecosystems by helping to control insect populations. Most spiders are harmless to humans, though a few species have venom that can be dangerous if they bite.
Spiders come in a wide variety of shapes, sizes, and colors. They build intricate webs to catch their prey, which consists mainly of insects and other small invertebrates. Spiders use their venom to immobilize their prey before wrapping it in silk and consuming it.