A dictionary, map, or table is a collection that stores data as key-value pairs. Instead of accessing items by a numbered index like an array, you access them by a unique key — which can be a word, number, or other identifier.

Think of it like a real dictionary — you look up a word (the key) and get its definition (the value). This makes them incredibly useful for storing related pieces of information together, like all the properties of a player in a game — their name, health, score, and level all stored under one variable.

The concept is the same across all four languages but the name differs — Java and C# call it a Map or Dictionary, JavaScript calls them Objects or Maps, and Lua uses its all-purpose Table for this as well as arrays.