A class is a blueprint for creating objects. Think of it like a template — you define a class once describing what properties and behaviors something should have, then you can create as many objects (also called instances) from that blueprint as you need.

For example, you might create a Player class that defines that every player has a name, health, and score, and can move, jump, and take damage. Every time a new player joins your game you create a new instance of that Player class — same structure, different data.

This concept is called Object Oriented Programming (OOP) and it's one of the most important programming paradigms you'll encounter. The four key pillars of OOP are encapsulation (bundling data and behavior together), inheritance (a class inheriting properties from another class), polymorphism (different classes sharing the same interface), and abstraction (hiding complex details behind simple interfaces).

Not all languages treat OOP the same way — Java and C# are built around it, JavaScript bolts it on top of a different system, and Lua has no built in class system at all but can simulate one using tables.