Programmers often make a distinction between compile time and run time .
Compile time is the period when a program is being compiled, while run time is the period when a program is running. The distinction is important, for example, in terms of the different types of errors that can occur. By this time you have seen many compile time error messages - error messages generated by syntactic errors in your code. In contrast, run time errors involve such things as trying to divide by 0. Such an error would not be caught at compile time because, at that point, the system does not know the values of the variables.