Bipolar transistors are transistors that contain both p-type and n-type material. They are used in many types of electronic circuits, and find their primary application in amplifier circuits. When a bipolar transistor is pre-biased, it means that has been setup with a bias voltage or current applied to its base/gate, causing it to be partially on. This partial turn on of the transistor can have several advantages compared to a non-biased transistor, such as increased speed and reduced power consumption. Pre-biasing a transistor can also reduce the amount of power needed to turn the transistor on, and therefore the size of the associated elements, such as the power supply. Pre-biasing is particularly useful in circuits where the operating parameters of the transistor vary over time, such as high-frequency circuits and RF applications.