A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. There are two types of transistor characteristics: (i) Input characteristics and (ii) Output characteristics. Input characteristics have different constant values of collector voltages (VCE), and are represented by the graph plotted between base voltage (VBE) and the base current (IB). Output characteristics have a constant value of base current (IB) and it is represented by the graph plotted between the collector-emitter voltage (VCE) and collect current (IC).
This video explains the static characteristic of a transistor (Common Emitter Configuration).