Spider silk is a fibre secreted by spiders.
Spider silk is a remarkably strong material; the strongest natually-occurring fiber known.
Its tensile strength is comparable to that of high-grade steel.
Spiders normally use their silk to make structures, either for protection for their offspring, or for predation on other creatures.
They can also suspend themselves using their silk, normally for the same reasons.
Many small spiders use silk threads for ballooning.
They extrude several threads into the air and let themselves become carried away with upward winds.