Parallel surfaces sharing one frame, of which one shows at a time. What is hidden is not gone, only behind.
English tab (a small flap or projecting piece), first recorded in the seventeenth century and of no securely traced origin; the interface sense borrows the physical filing-tab, a labelled flap that lets one folder be found among others stacked behind it.
Parallel surfaces sharing one frame, of which one shows at a time. What is hidden is not gone, only behind, the way a labelled flap sits behind the ones in front of it.