The Pomodoro clock is a tool to assist plan your time, when you do learning or other type of exercise/activity. Foramlly we call session the active period, when you work on your assigment. Break is when you rest. Generally, you want for example to study in sets of 40-50mnts and have a rest time for about 5-10 mnts. When you use a Pomodoro clock, it starts with session, for example 40 mnts, after this time ends the break time start(say 10 mnts). Once the break time ends, another session time commence and this goes on till your assigment is complete, or you decide its time to wrap it up