The 2N2222A belongs to a sort of NPN bipolar junction transistor, used for general purpose low-power amplifying or switching applications. It is designed for high speed switching application at collector current up to 800mA, and features useful current gain over a wide range of collector current, low leakage currents and low saturation voltage. The major functional area of 2N2222A is enclosed in TO-18 package. Due to the low cost and small size it is the most commonly used transistor. One of its key features is the ability to handle the high values of currents as compared to the other similar small transistors.
2N2222A transistor works in low to medium current, low power, medium voltage, and can operate at moderately high speeds. the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin