Roleplaying Games (or RPG's for short) are very much like an improvised play. Each player has his or hers character (which can be very different to who he or she really is), which he portrays in the game world (which, again, could be very different to the real world).
One player, however does not play a character. This player is called the Game Master (GM for short), or Storyteller (ST) or Dungeon Master (DM). He is in charge of playing the rest of the world - all the people and creatures the player characters encounter, and to describe the world and the environment itself. The GM is also the arbitrator of whether or not certain actions succeeded. If a player decides to raise his sword and attack an ogre, the GM is the one the decides (with the help of the game rules and some dice, usually) if he hit the ogre or not, and what effect did that blow have on the poor ogre.
A difference between Roleplaying Games and other types of games which a lot people find hard to grasp is the complete lack of a board, a computer screen or any other way of comprehending the game. The game goes on inside the players minds, played only with their imagination.
However, a roleplaying game does have some aids to the players imagination. Most roleplaying games have a rule book (or several) which lay done the rules of the world. These rules determine what the player characters can and cannot do, and how to check if they succeeded in doing so. Some games use dice of all forms and shapes to provide an aspect of randomness to the game (after all, even the mightiest warrior misses sometimes).
Some players also like to use other props such as candles, model weapons and appropriate music to "get in the mood" of the game, but this is definitely not compulsory.
In every other type of game, be it a card game, a strategy game, a board game or a ball game, there is always an objective. There will always be a winner and a loser, and the game is played in order to win. In solitaire you need to clear the board of all the cards. In chess you need capture your opponents king. In monopoly you need to accumulate the most money, and leave the other players broke. In soccer you need to score more goals than your opponent.
Roleplaying games are different. In roleplaying games, there is no final objective. There are no winners and losers. The only objective the game has is to be creative and to have some fun. Sure, there could be small objectives (or quests) on the way - the characters might need to save a princess from an evil warlock or slay a dragon menacing the village. But even if they do not succeed in doing so, they didn't "lose" the game. As long as they (the players, not the characters) enjoyed the game, they have fulfilled its objective.
Let your imagination roam free. Dare to step out of the boundaries of yourself. Be a roleplayer.
Ogmios and The Ogmios Project staff will be here to assist you on every step of the way, should you need help.