Some old words were given new meanings, such as mail (which now means email). This makes many metaphors on the Internet, such as boot (which otherwise mean a shoe) and link (which otherwise means a joint in a metal chain). Some existing acronyms, such as "AFK" (To mean "Away from keyboard") and "IRL" (To mean "In real life") were used on bulletin board systems before the internet became popular. These are now used on the internet, such as in chat rooms and on instant messenger software.