Time is of philosophical interest as well as the subject of mathematical and scientific research. Even though it is a concept familiar to most, the passage of time remains one of the greatest enigmas of the universe. The philosopher Augustine once said: "What then is time? If no one asks me, I know what it is. If I wish to explain it to him who asks me, I do not know." The concept time indeed cannot be explained in simple terms. Emotions, life, and death - all are related to our interpretation of the irreversible flow of time. After a discussion of the concept of time, Prof. Mazur will review historical attempts to "stop time", that is, to capture events of very short duration and then present an overview of current research into ultrafast processes using short laser pulses.