In truth, spiders are extremely beneficial because they prey on many insects that we consider to be pests in our homes and gardens. Not all spiders build webs to snare their prey.
Some species ambush their prey from tubular tunnels built in the ground or under rocks.
Other species simply build a loose collection of webbing in which they live. The types of spiders that most frequently invade homes fit into these latter categories. They may remain hidden for most of the day and feed primarily at night. Spiders are not insects. They are close relatives of ticks, mites and scorpions, which all belong in the group called arachnids.