As the name says, these errors occur when running the programming.
The user/programmer asks the computer a task, but the computer is unable to execute the task.
For example:
- Trying to divide by a variable that contains a value of zero
- Trying to open a file that doesn’t exist
The programmer will mostly find these errors after testing his program. So after submitting a legit project a runtime error shouldn’t occur by itself.
However, a runtime error can occur, after executing user input, if the program isn’t written well. Read more about dealing with runtime errors from user input here.