illegal else without matching if

This is a syntax error that occurs when an else statement is used without a corresponding if statement. In programming, the else statement is used to specify what should happen when a certain condition is not met. However, for the else statement to be valid, there must be a previous if statement to which it corresponds.

For example, consider the following code:

if x > 0:
    print("x is positive")
else:
    print("x is not positive")

In this code, the else statement is used to specify what should happen if the condition in the if statement (x > 0) is not met. If x is greater than 0, the first statement will be executed. If not, the second statement will be executed.

If you were to remove the if statement and just leave the else statement, you would get an "illegal else without matching if" error:

else:
    print("x is not positive")

This is because there is no if statement to which the else statement corresponds. To fix this error, you need to add the if statement back in or remove the else statement entirely.