A condenser microphone has a capacitor system in which two plates with voltage between them create sound. http://www.thefreedictionary.com/condenser+microphone It is a good choice for recording vocals in a studio environment and can be used in a live setting as a drum microphone. http://www.bethanystudio.org/MicrophoneInfo.htm The outerplate, or diaphragm, of the system is usually made of a thin material that vibrates when sound waves strike it. The vibration changes the distance between the two plates, changing the capacitance (the ability to hold an electric charge). http://www.bethanystudio.org/MicrophoneInfo.htm For this to happen, a voltage must be present between the two plates, so a condenser microphone must be powered. This process causes the microphone to be extremely sensitive to vibrations, thus a poor choice for louder projects that may cause distortion. http://www.bethanystudio.org/MicrophoneInfo.htm

A condenser microphone is not the best choice for recording louder or amplified instruments, but in a live setting such as a studio environment they are ideal. http://www.bethanystudio.org/MicrophoneInfo.htm Condenser microphones usually come in two varieties. The large diaphragm condenser will produce a warmer sound suitable for vocals. A small diaphragm condenser will produce a brighter sound, preferable for recording stringed instruments. To increase versatility of the condenser microphone, some combine the two diaphragms, with the large on one side of the microphone and the small on the other. http://www.homerecordingfun.com/home-recording-hardware/microphone/condenser-microphones Condenser and dynamic microphones are the most common, with both using a transducer to convert sound energy into electrical energy. Dynamic microphones create sound using electromagnetic induction, and tend to be more resilient. http://www.bethanystudio.org/MicrophoneInfo.htm The condenser is often more expensive and more fragile, but produces a stronger audio signal making them ideal for capturing subtle nuances in a sound. http://www.bethanystudio.org/MicrophoneInfo.htm

The electret condenser microphone (ECM) uses a special type of capacitor, which has permanent voltage built-in. It is like a permanent magnet since it does not require external power to operate. http://www.digikey.com/Web%20Export/Supplier%20Content/PUI_668/PDF/PUI_ElectretCondenserMicrophone%20Basics.pdf The ECM principal of operation is that sound waves impinge on the diaphragm, causing the capitance between it and the back plate to change at the same time. In turn, this induces an AC voltage on the back plate. http://www.digikey.com/Web%20Export/Supplier%20Content/PUI_668/PDF/PUI_ElectretCondenserMicrophone%20Basics.pdf The best ECMs usually include a pre-amplifier, which still require power. Otherwise, ECMs are the same as normal condensers. http://www.mediacollege.com/audio/microphones/condenser.html