What is the difference between deepcopy and copy in Python

Short answer

copy.copy creates a shallow copy (new container, same inner objects), while copy.deepcopy creates a fully independent clone of an object and everything it contains.

Details

A shallow copy is usually enough for flat lists or simple structures, but nested objects still share references. For example, copying a list of lists with copy.copy means modifying an inner list affects both originals. In contrast, copy.deepcopy recursively clones every object it encounters, which is safer but slower and more memory-intensive. Understanding object identity matters when you work with Python classes and objects, since mutable attributes are a common source of bugs. Deep copying is also useful when transforming data in list comprehensions that you later want to modify independently. Always wrap risky copy operations in try/except blocks when dealing with custom objects that may raise exceptions during duplication.

Tips

• Use slicing (new = old[:]) or list(old) for shallow copies of simple lists.
• Avoid deepcopy on objects containing infinite recursion unless you implement __deepcopy__.
• Profile memory usage when deep copying large data structures in production code.