For the past few weeks, I've noticed a big, brown spider outside my front door resting on an equally big circular web. The web itself was about 2 feet wide and I certainly couldn't walk out the door without stepping right into it. It seemed to appear and begin spinning the web around 9pm and by 6am the following morning, the web and the spider were gone - only to appear in the same spot the following evening.
The Nocturnal Orb Weaver is a garden spider that comes out at night, creates a big "orb" shaped web and waits for an unsuspecting insect to land in the sticky web (most likely attracted to the lights by the door to the house). They are most noticeable in the late summer and fall because that's when the spiders and their webs are the largest. It's usually the female sitting in the web and soon she will lay her last batch of eggs and die before the first frost.
They are non aggressive and not harmful to humans or animals. In fact, at the first sign of threat, they usually flee the scene. During the day, the spider will either sit motionless on the web or take cover in a nearby leaf or corner.
Fun fact: Charlotte, the spider in E.B. White's "Charlotte's Web," was an orb weaver. She was an Araneus cavaticus, sometimes called a "Barn Spider."
All orb weavers spin some sort of web consisting of smaller circles within larger circles and the "spokes" going out diagonally from the center outwards toward the outer circle.
So if you see one outside your front door or on your lawn over the next few weeks, don't be alarmed and let them just do their job catching and eating common insect pests.