'NameError' occurs when you try to access a variable or function that has not been defined. Check for typos, ensure the variable is defined before use, and confirm that it's in the correct scope.

'NameError' is an exception that occurs in Python when you attempt to access a variable, function, or object that has not been defined in the current scope. This can happen for several reasons, such as typos in the variable name, using a variable before it has been declared, or trying to access a variable from an outer scope that is not available in the current context. To resolve a NameError, start by checking the spelling of the variable or function name, ensuring that it matches the definition exactly. Next, verify that the variable has been defined before you try to use it; if the variable is conditionally defined, ensure it is initialized in all code paths. Also, consider scope; if you're working with nested functions or classes, confirm that the variable is accessible within the intended scope. By systematically identifying the source of the NameError and addressing it, you can ensure your Python code runs smoothly.