Spiders are incredibly diverse, and there are tons of them. It's estimated that 90,000 species exist on every continent on the planet except Antarctica; around 40,000 have been definitively identified. While they may elicit only a few predictable reactions from many people, they exhibit a wide range of behaviors and characteristics themselves.
However varied their habits and habitats may be, they do have some things in common. They all make silk in some form, and the composition of their silk reflects their variation. Spiders all have some kind of venom as well, which is different from species to species. Scientists have tried to classify spiders along behavioral and morphological lines, but are now beginning to look to genetics to study them.
Researchers have been able to look at the genomes of many different spiders, and it has given them new information about how various behaviors evolved. That knowledge has upended the way researchers thought of spiders and what was assumed about how they developed into the many species we live with today.