The spread operator is a new addition to the set of operators in JavaScript ES6. It is denoted by three dots, ..., and allows an iterable, such as an array or string, to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected. The spread operator can be used in three distinct places: function arguments list, array literals, and object literals.

• Function arguments list: The spread operator can be used to pass an array as individual arguments to a function. For example, myFunction(a, ...iterableObj, b) .
• Array literals: The spread operator can be used to combine two or more arrays into a single array. For example, `.
• Object literals: The spread operator can be used to enumerate the properties of an object and add the key-value pairs to the object being created. For example, { ...obj, key: value } .

The spread operator is often used in combination with destructuring. It can be used to make deep copies of JS objects, where the spread operator makes a deep copy of top-level data and a shallow copy of the nested data. The spread operator is also used to clone an array, as objects are assigned by reference and not by values in JavaScript.

Overall, the spread operator is a useful tool for working with arrays and objects in JavaScript, allowing for more concise and readable code.