Spiders are predators. They are only in your home because they have enough food to stay alive. They are feeding on the little pests that you don’t see. Most people dislike having spiders and spider webs in or on their homes. There are often blood stains under the webs. Outdoors, spiders are everywhere, but especially near lights or water (easy places to catch prey). You will often see egg sacs/casings (the ootheca) in spider webs.
They can be various shades of white, yellow, and brown. Each egg sac will contain 50-200 baby spiders. Mother spiders are very defensive of their egg sacs, so do not disturb them, especially if you see the spider. If the egg sacs are not removed, the spiders will hatch out, spread out over all the surrounding areas, reaching adulthood in 3-12 months.