Immutable objects are data structures that cannot be changed after they are created. This means that once an immutable object is defined, its state or value remains constant throughout its lifetime. Examples of immutable objects include strings in Python and Java, where any modification results in the creation of a new object rather than altering the original. The primary benefit of using immutable objects is that they enhance program reliability and simplify debugging. Since their state cannot change, they help prevent unintended side effects in code, making it easier to understand and maintain. Additionally, immutable objects can improve performance in certain scenarios, such as when used in functional programming.