The name "Collembola" is derived from "Colle" = glue and "embolon" = piston or peg. This refers to the belief that the ventral tube has adhesive properties, that is, that it is a "glue-peg". However, the tube's function is primarily for excretion and maintaining water balance.
Springtails have the widest distribution of any hexapod group, occuring throughout the world, including Antarctica. They are probably the most abundant hexapods on Earth, with up to 250,000,000 individuals per square acre. They are found in soil, leaf litter, logs, dung, cave, shorelines, etc. There are about 6000 known species.
The one I photographed today, I found under a disguarded beer can in local woodland close to my home in Cranbrook Kent (U.K.)
A Globular Springtail-Dicyrtomina saundersi-Around 3mm