What is transistor saturation?

Could anyone help me about transistor saturation?

• please help me about transistor saturation.. i have a report on monday,, i don't understand from the book.. please help me, what it is,and what is the function of transistor saturation THANKSSS

• Answer:

  When a transistor is saturated, it is conducting as much current as it can in the circuit. The collector is shorted as nearly as possible to the emitter. When the transistor is in the linear region, like for an amplifier, an increase in base current will increase the collector current. But when the base current times the gain is more current than is available in the collector circuit, the transistor turns on hard, and the collector voltage goes down to a few tenths of a volt. This is a good thing when you are controlling a digital circuit, or turning on a light, because when the transistor voltage is low the load gets most of the voltage, and the transistor dissipates less power (V x I).