Roleplaying games (RPGs) are open-ended games in which a person or a group of people (usually called games masters (GMs) or dungeon masters (DMs)) create an open-ended story-based adventure. Each player creates one or more characters and decides what actions those characters take within the game based on traits that are specific to their characters.

The games are a combination of storytelling and improvisational theater (“improv”). Players decide what their character would do or say, and describe it or act it out. Other players decide how their characters would respond, and describe or act out their response. The entire session continues in this manner.

Characters have traits that usually fall into the following categories:

• Species or sub-species. This is usually called race, but the word “race” in RPGs is often used in the sense of J.R.R. Tolkien's Lord of the Rings books, including elves, hobbits, dwarves, orcs, humans, etc.
• Character abilities. These are descriptions of the character's inborn abilities. Typical character abilities include strength, intelligence, wisdom, dexterity, health and charisma.
• Character class. These are like professions. Each game system has its own list, including various types each of fighters, spellcasters, healers, rogues, entertainers, etc.. As characters gain experience, they gain more special abilities that are specific to their class.
• Alignment. This is a character's tendency to help others (“good”) vs. be self-serving (“evil”), and to follow rules or their own moral code (“lawful”) vs. do whatever the situation seems to call for regardless of rules or customs (“chaotic”).
• Personality and backstory. As long as these fit within the constraints of the above traits, these are whatever the player decides. Be creative!

In these games, the object is for the GM to create a setting and story line that usually includes challenges that the characters have to overcome (with the players deciding how to do this). The outcome is designed to be achievable, but usually requires cooperation among players and clever use of ingenuity in combination with the characters' abilities.

Some game actions involve roleplaying hostile actions against other characters. (For example, you might have to fight and kill some zombies.) There are specific rules and game mechanics for simulating physical combat and magic. In tabletop RPGs, this is usually done by rolling dice and comparing the result against some threshold. In LARPs, this might be done with padded boffer weapons and beanbags to make the combat look and feel realistic enough to simulate what's happening in the game, but in a way that ensures safety for the players.