Python 'is' vs '==': Why Using the Wrong Operator Can Break Your Code

In Python, the '==' operator checks whether two objects hold the same value, while 'is' checks whether two variables point to the exact same object in memory. Using them interchangeably can cause unexpected bugs, particularly in complex applications. For example, two separate lists with identical contents will satisfy '==' but fail an 'is' check, since they occupy different memory locations. Checking for None is a common exception where 'is' is actually the recommended approach, because None is a singleton object in Python. Developers should also avoid using 'is' to compare numbers or strings, as Python's internal caching of small integers and string interning can produce misleading results.