What is in simple words blocking IO and non-blocking IO?

Question

How would you explain a simple mortal about blocking IO and non-blocking IO? I've found these concepts are not very clear among many of us programmers.

Answer 1

Blocking I/O means that the program execution is put on hold while the I/O is going on. So the program waits until the I/O is finished and then continues it's execution. In non-blocking I/O the program can continue during I/O operations.