Springtails (Collembola) are hexapods but not insects, being members of the insects’ sister class Entognatha (which also includes proturans and diplurans). They are tiny (<6mm), and numerous, occurring at densities up to around 100,000 per square meter of topsoil. They are important components of forest floor ecosystems, and some species can also be found floating on the surface of stagnant water.
Their name comes from the tail-like furcula folded beneath their body which is used for jumping (see video below).
Here is another video from Preston Guerra of some springtails: