How do transistors amplify the current?

Transistor does not actually amplify the magnitude of current. When a small voltage is applied to the Base of NPN transistor, it "allows" the Larger amount of current to be passed, through the Collector to the Emitter. 

Hi,

Dear there are many types of transistors which are used for the amplify purpose. i.e NPN or PNP etc.

Each have different methodology to operate and execute the operation.

Thanks.