Many VPN software use the TUN or TAP kernel driver to create a virtual network interface (mainly for Linux and FreeBSD systems). I know how they work and the differences, this is purely a lexicographic question.
Just out of curiosity, what actually mean TUN and TAP? Are they acronyms? I can't find much on internet, someone says TUN is a shorthand for tunnel, but I can't find any confirmation of this. Neither Wikipedia nor the kernel documentation provide the expansion for the acronyms. Not even the original sourceforge website.