Have you ever been walking outdoors and suddenly felt a cobweb on your face? It feels as if you'd just walked through a spiders web, and yet there was definitely no web in front of you. If you've experienced this, it's highly likely you had a collision with a flying spider!
On warm, breezy days spiders are able to move to new locations by literally 'ballooning' through the air. They find a high location to act as a launch pad. Then they let out a long line of silk. When the silk gets caught in the wind it rises up and takes the spider with it. Landing is a bit haphazard, but hey, if you break a leg at least you've got another seven spare.
This method of aerial dispersal using silk is also practiced by spider mites and some moth larvae. It's not known exactly when it was first employed, it could have been at the same time these creatures evolved silk production, or possibly when deciduous trees appeared in the Cretaceous period. They make great launch pads. Either way, it has contributed to the successful survival of many species by helping them to colonise more suitable habitats.