The Three Pillars of Adventure

Introduction to Adventuring

The Dungeons & Dragons game consists of a group of characters embarking on an adventure that the Dungeon Master presents to them. Each character brings particular capabilities to the adventure in the form of ability scores and skills, class features, racial traits, equipment, and magic items. Every character is different, with various strengths and weaknesses, so the best party of adventurers is one in which the characters complement each other and cover the weaknesses of their companions. The adventurers must cooperate to successfully complete the adventure.
The adventure is the heart of the game, a story with a beginning, a middle, and an end. An adventure might be created by the Dungeon Master or purchased off the shelf, tweaked and modified to suit the DM's needs and desires. In either case, an adventure features a fantastic setting, whether it's an underground dungeon, a crumbling castle, a stretch of wilderness, or a bustling city. It features a rich cast of characters: the adventurers created and played by the other players at the table, as well as nonplayer characters (NPCs). Those characters might be patrons, allies, enemies, hirelings, or just background extras in an adventure. Often, one of the NPCs is a villain whose agenda drives much of an adventure's action.
Over the course of their adventures, the characters are confronted by a variety of creatures, objects, and situations that they must deal with in some way. Sometimes the adventurers and other creatures do their best to kill or capture each other in combat. At other times, the adventurers talk to another creature (or even a magical object) with a goal in mind. And often, the adventurers spend time trying to solve a puzzle, bypass an obstacle, find something hidden, or unravel the current situation. Meanwhile, the adventurers explore the world, making decisions about which way to travel and what they'll try to do next.
Adventures vary in length and complexity. A short adventure might present only a few challenges, and it might take no more than a single game session to complete. A long adventure can involve hundreds of combats, interactions, and other challenges, and take dozens of sessions to play through, stretching over weeks or months of real time. Usually, the end of an adventure is marked by the adventurers heading back to civilization to rest and enjoy the spoils of their labors.
But that's not the end of the story. You can think of an adventure as a single episode of a TV series, made up of multiple exciting scenes. A campaign is the whole series—a string of adventures joined together, with a consistent group of adventurers following the narrative from start to finish.

The Three Pillars of Adventure

Adventurers can try to do anything their players can imagine, but it can be helpful to talk about their activities in three broad categories: exploration, social interaction, and combat.
Exploration includes both the adventurers' movement through the world and their interaction with objects and situations that require their attention. Exploration is the give-and-take of the players describing what they want their characters to do, and the Dungeon Master telling the players what happens as a result.
On a large scale, that might involve the characters spending a day crossing a rolling plain or an hour making their way through caverns underground. On the smallest scale, it could mean one character pulling a lever in a dungeon room to see what happens.
Social-interaction features the adventurers talking to someone (or something) else. It might mean demanding that a captured scout reveal the secret entrance to the goblin lair, getting information from a rescued prisoner, pleading for mercy from an orc chieftain, or persuading a talkative magic mirror to show a distant location to the adventurers.
Combat, involves characters and other creatures swinging weapons, casting spells, maneuvering for position, and so on-all in an effort to defeat their opponents, whether that means killing every enemy, taking captives, or forcing a rout. Combat is the most structured element of a D&D session, with creatures taking turns to make sure that everyone gets a chance to act. Even in the context of a pitched battle, there's still plenty of opportunity for adventurers to attempt wacky stunts like surfing down a flight of stairs on a shield, to examine the environment (perhaps by pulling a mysterious lever), and to interact with other creatures, including allies, enemies, and neutral parties.

The Wonders of Magic

Few D&D adventures end without something magical happening. Whether helpful or harmful, magic appears frequently in the life of an adventurer.
In the worlds of Dungeons & Dragons, practitioners of magic are rare, set apart from the masses of people by their extraordinary talent. Common folk might see evidence of magic on a regular basis, but it's usually minor—a fantastic monster, a visibly answered prayer, a wizard walking through the streets with an animated shield guardian as a bodyguard.
For adventurers, though, magic is key to their survival. Without the healing magic of clerics and paladins, adventurers would quickly succumb to their wounds. Without the uplifting magical support of bards and clerics, warriors might be overwhelmed by powerful foes. Without the sheer magical power and versatility of wizards and druids, every threat would be magnified tenfold.
Magic is also a favored tool of villains. Many adventures are driven by the machinations of spellcasters who are hellbent on using magic for some ill end. A cult leader seeks to awaken a god who slumbers beneath the sea, a hag kidnaps youths to magically drain them of their vigor, a mad wizard labors to invest an army of automatons with a facsimile of life, a dragon begins a mystical ritual to rise up as a god of destruction—these are just a few of the magical threats that adventurers might face. With magic of their own, in the form of spells and magic items, the adventurers might prevail!