This illustration1 shows the end of an Isotoma leg (Entomobryomorph). There are three pairs, the legs are attached to the three thoracic segments. Springtails uses them to move, but also for other operations such as the toilet. See this video3 (Sminthurinus reticulatus) or this other video3 (Sminthurinus aureus).
Legs of Symphypleones:
In Entomobryomorphs and Symphypleones (first image, below2, Legs of Dicyrtomina), the different parts are generally very visible, whereas in Poduromorphs (second image below) the legs are very short and their segmentation, although the same is often not very discernible.
Legs of Poduromorphs:
1: Right image taken from a photograph by J-P. Marino on the Aramel site.
2: Photos © Philippe Garcelon.
3: Videos from my gallery "FLICKR", shot with a trinocular magnifier.