Array concatenation is the process of joining two or more arrays to create a single array. This operation combines the elements of the original arrays in the order they are provided, resulting in a new array that contains all the elements from the input arrays. For example, if you have an array A with elements [1, 2] and another array B with elements [3, 4], concatenating them would produce a new array [1, 2, 3, 4]. In programming, many languages provide built-in functions or methods to perform array concatenation easily. For instance, in JavaScript, the `concat()` method can be used to merge arrays, while in Python, the `+` operator can achieve the same result. This operation is useful in various applications, such as data manipulation and combining datasets.