What's the difference between `os.environ` and `os.getenv()`?

Both `os.environ` and `os.getenv()` are used to access environment variables. `os.environ` returns a dictionary-like object, requiring you to use square bracket notation (`os.environ['variable_name']`). `os.getenv()` directly returns the value of the environment variable, or `None` if the variable is not found. `os.getenv()` is generally preferred because it avoids `KeyError` and provides a more concise way to retrieve environment variables.