LARP stands for Live Action Role Play, it consists of playing a role in real life, that is outside of any board games or video games, using your own bodies as the avatar of your character and live props of relevant size and imagination to fill in the blanks (much like in your average board game RP session).
People of all ages can LARP and no special equipment is required. Children are more prone to LARP as they think less about maintaining their image and are thus more free to make themselves look as silly as they will during a session of LARP.
LARP is often centered around fantasy games, movies or stories with a medieval theme, such as Dungeons and Dragons, Lord of the Rings and even creatures from old folklore such as vampires and werewolves. Occasionally people LARP around concepts with more modern themes such as Harry Potter, sports and modern war. LARP based on futuristic concepts such as Star Trek or Star Wars is also popular. So basically any fantasy a person can hold can be turned into LARP.
We all know the general image of the D&D LARP player, running around often using rules from game books to decide upon events in their LARP, but you can also just ditch any rules, if you′ve ever seen children running around with toy guns shooting at each other, pretending to die when a well aimed shot from a NERF gun hits them, then that is LARP. If you′ve seen children play doctor, or pretend to be a star athlete during a game of for example football, then that is LARP, if you′ve ever seen girls set up a tea party with a plastic kettle and plastic tea cups, sipping away from empty cups, then that is LARP.
I don′t think anyone really goes through childhood without doing some LARP. To take an example from my own childhood me and my friends used to LARP using the game Heroes of Might and Magic as our basis, we′d find a good playground, designate big buildings as castles and then decide upon turns and what each of us would do each turn, we′d give things in the area the role of many different mines, and we′d imagine up battles against imaginary enemies that we′d be likely to see at such places from the games, using rules from the games, often straining our little minds with all of the details we were trying to remember through it all... (if you′ve ever played a game of Heroes of Might and Magic, then imagine having to try and remember the price of each structure, the basic number of steps a fresh character could take, the kind of XP you′d get from your average fight, how much creature growth there was of each creature and so on and so on).
So if you′ve not done LARP at least once in your life I find that to be pretty weird and unique, but if you did but didn′t realize it then now you know what the concept of LARP is about.
Unfortunately. Some of us are in a cold, dark, lonely workspace when everyone has long since left, filling out a database and correcting other peoples mistakes.
Forgive me if I decide to come on a forum between checks and fixes to reply to stuff.
Not all of us are lucky enough to be unemployed 
Well if you′ve worked so hard on your life you must be a pretty big success and you must have a mate. Such pairs often engage in LARP through roleplay in their more intimate moments. And yes, that counts as LARP too.