Spiders do not fly with wings as some insects and birds are able. However, they are able to travel through the air by sending out a bit of silk which captures a breeze.
Spiders wanting to travel by air will go up as high as possible on a tree or plant and then cast out a silk line. This silk line is caught by a breeze or wind, which contorts the silk thread into a balloon like "sail." Spiders are able to sail on the wind over hundreds of miles to ships at sea or remote islands. Baby spiders have been known to sail for up to 25 days with food. Unfortunately, spiders are unable to determine where they will land while "sailing."