VPL or visible panty line is the outline of the edge or seam of someone's panties visible across their buttocks under a skirt, dress, leggings, trousers, catsuit, etc. This may be an indentation caused by a tight or elasticated edge, or a thick hemline, or the outer garment may be slightly see-through; for example, tight leggings may have this effect . The same effect may be produced by the bottom hem of a leotard or legless bodysuit.
VPL is often more conspicuous when someone is walking upstairs, since bending the legs at the hips tightens the clothing over the buttocks.
Normally, only the lower edge of the underwear is visible. However, the top may also be visible, especially when there is see-through.
A related phenomenon is that the top of the underwear may be visible over a low waistband of a skirt or trousers. This seems to happen more often with thongs than with other underwear (see whale tail).