Going to the same well twice, this week, but only because I did such a poor job on Monday, and should have written about origami, instead (I may go write a supplemental entry, a la Star Trek 8-).
What is a roleplaying game, or RPG, and why is it the central preoccupation of my life? 8-P
Roleplaying is 'Let's Pretend' with rules. Sometimes those rules are very simple; other times, not so much. It's like improv, improvisation, an actors exercise or Drew Carrey's 'What's My Line?' Tabletop RPGs are also what I refer to as tabletop entertainment, and involve, naturally enough, a group of people sitting around a table with character sheets, dice, and often food and drink, the mortal enemies of character sheets everywhere...
Character sheets are sort of the board we play the game on, if RPGs can be said to have a playing surface. They are where were write down the facts and foibles of the Player Character, or PC, which is sort of your playing piece in the game. You control it; if you created the character, you selected or rolled up all the stats and numbers you will use in play. He, she or it is you, in the game, but not you, the real world person (if you don't ever get caught up in the game so much that the distinction blurs, then you aren't roleplaying! 8-).
Dice are a social fiction, a randomizer that allows us to risk, to gamble, to succeed or fail without knowing beforehand what the outcome with be. They can be extremely useful and informative, or the despair of many a player, when they roll low, when you needed a high number, or high, when you needed low. There are a lot of gamers that don't like that much randomness, and there are all kinds of ways, in all kinds of different systems, for the player to take more control over the course of events (and some games don't even use dice at all).
At the heart of it, there's what you know about your character, what you know about the world and the people in it that the game master or narrator has described for you, and there's what you want your PC to do. Everything else is figuring it all out, sort of like telling the story, shooting the movie, or writing the book as you go along. You are part of what makes this a great fight sequence, or that a thrilling hostage negotiation, and you are the bard, singing a ballad, the hero, slaying the monster, or part of the band of adventurers, saving the kingdom.