What does the `concat()` method do in JavaScript?

The concat() method in JavaScript is specifically designed to merge two or more arrays and return a new array containing the elements of the original arrays combined together. When you use concat(), it does not alter the existing arrays but instead creates and returns a new array that includes the elements from both the original arrays and any additional arrays you may provide as arguments.

This method can be particularly useful when you want to combine data from multiple sources or when you need to create a unified array without modifying the original data structures. For example, if you have one array of numbers and another array of more numbers, employing concat() allows you to seamlessly produce a single array with all those values.

By contrast, some of the other methods mentioned relate to manipulating the order or contents of an array, such as changing the order of elements, adding elements to the end, or removing elements from the end, none of which describe the functionality provided by concat(). This focus on merging arrays is the key feature that distinguishes it in JavaScript array manipulation.