Q. Regions of operation in BJT ?

Transistor find many applications like amplifier, switch etc. depending upon the polarity and the magnitude of the applied voltages across the junctions, there are three distinct regions which a bi-polar junction transistor can  be operated ,when the transistor is configured for a particular application ,it must be operated in a particular region. There are three regions in which we can operate a transistor they are the active region, the cut-off region and the saturation region.

When the emitter junction is forward biased and the collector junction is reverse biased the region of operation is the active region and when both the emitter junction and the collector junction is forward biased the transistor is said to be in the saturation region. When  both the emitter junction and   the collector junction is reverse biased the transistor is said to be in the cut-off region.