What does biasing a transistor mean?

Answer 1

It means, applying voltages and currents (usually through properly placed, proper valued resistors) to cause the transistor to operate in the region where you want it to operate (near cutoff, or in the linear region, or near saturation).

Example: in the linear region, in a common emitter amplifier configuration, and with no signal applied; the base-to-emitter junction will be forward biased (that diode will be 'on'), and there will be some collector current flowing.

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