What is the main difference between a list and a tuple in Python?

In Python, the key distinction between a list and a tuple is based on mutability. A list is mutable, meaning that once it is created, the elements within it can be changed. This includes the ability to add, remove, or modify the elements at any point in the program. This characteristic allows lists to be flexible and dynamic, making them suitable for various operations where the contents need to be updated or modified over time.

On the other hand, a tuple is immutable, which means that once a tuple is created, its contents cannot be altered. You cannot add, remove, or change the elements of a tuple after its creation. This immutability provides certain advantages, such as ensuring that the data remains constant throughout its use, which can lead to improvements in performance and efficiency in some contexts. Additionally, tuples can be used as keys in dictionaries since their contents cannot change, whereas lists cannot due to their mutable nature.

The nature of these data structures informs their use cases: lists are often used for collections of items that need to be modified, while tuples are used when a fixed set of values is needed, enhancing reliability and preventing accidental changes.