Immutable collections are data structures that cannot be modified after they are created. This means that once you create an immutable collection, you cannot add, remove, or change its elements. This property makes them useful in programming, as they help prevent unintended side effects and make code easier to understand and maintain. In many programming languages, such as Java and Python, immutable collections are available as built-in types or libraries. They are often used in functional programming, where immutability is a key concept. Examples of immutable collections include tuples in Python and List.of() in Java.