Final answer:
In Python, an identifier can be any combination of letters, digits, underscores, and special characters as long as it doesn't begin with a digit.
Step-by-step explanation:
In Python, an identifier is a name used to identify a variable, function, or other object. According to Python rules, an identifier can be any combination of letters, digits, underscores, and special characters as long as it doesn't begin with a digit. For example, 'my_var', 'my_var2', and '_my_var' are all valid identifiers in Python.