A common device available in all kinds of sizes and at times built for specific purposes. From allowing us to converse over a phone to sing at a concert venue; the uses of microphones are diverse. There are only a few different types more commonly in use today. Dynamic and Condenser microphones being the most common.
One of the most used pieces of technology present in every phone, laptop and countless other devices, the microphone is a transducer - a device that converts energy from one form into another. In this instance converting sound into electrical signals so the sound can be reproduced through a speaker. Used for real-time purposes such as phone calls or for recording, like when a singer records the vocal layer of a song. Microphones are also called mics or mikes for short. A lot of microphones need to be connected to a pre-amp so the signal coming from them can be amplified before it is sent to a recorder, or a sound system without which the sound might be quite low and digitally turning it up would add noise and distortion.
Based off various technologies over time, the essential purpose is the same to capture sound. The most commonly used microphones are the dynamic microphone and the condenser microphone - after these two comes the crystal microphone. The dynamic microphone is used most as it is rugged, resistant to moisture and relatively inexpensive. It is also able to handle loud sound without generating feedback through the speakers, this ability coupled with the other pros makes it crucial to live performances. Condenser microphones require a power source and are more ideal for studio recordings or use in labs and are more suitable because they can pick up sounds that are very low, as the sensor inside has a smaller mass to be moved by vibration. Essentially, in a condenser microphone unlike other microphones, the sound has to do lesser work for the signal to be picked up. The crystal microphones work better as contact microphones that pick up vibrations from objects rather than the air or in harsh environments such as recording underwater. The contact ability also helps with acoustic equipment like a drum kit.
Directional and other differences
Microphones are designed with different sound directional capture abilities as some pick-up sound from all angles and some more from the front Vs. the back. This depends on where the microphone has to be used and for what. Noise-cancelling microphones are also common allowing for the sound you want to be picked up and other ambient sounds to be dimmed resulting in a more clear base signal. At concerts, this is very helpful when the shouting of the crowd doesn't get added into the singer's mic as much, retaining the essence of his or her voice or in aeroplane cockpits the general noise is cut out so the pilot is more audible. Some of these work based on two diaphragms as one diaphragm picks up the main source of the sound the other picks up the ambient sounds and subtracts those or by a single diaphragm being placed closer to one port and inversely father from the other port. The port the diaphragm is closer to being the main source in this case.
More specific microphones
Some microphones are purpose-specific, so varied sizes or shapes along with attachments. Like the ones that have a dish (parabolic reflector) component that focuses sound coming from a distance into a microphone attached at its centre. Wireless microphones are also common that are used at concerts or for giving presentations. Providing the advantage of more mobility over a stage or around a hall. Stereo microphones have 2 microphones combined into one so the signal isn't split digitally but is true stereo and are useful for outdoor recording as it would be less convenient to set up two separate microphones to capture a more complete soundscape.
Connecting to one
Connectivity-wise microphones are either tethered using an XLR, TRS, TRRS, USB or a fibre optic line. The qualities vary but are comparable. Only an extremely trained ear might be able to tell more of a difference after hearing recordings from even the same microphone connected with different cables.
Companies produce different kinds of microphones under the same umbrella so one brand might be making 3 different kinds of microphones depending on user requirements. Commonly known brands include Shure, Sennheiser, Neumann (also owned by Sennheiser), Rode, AKG, Electro-Voice, DPA and Royer Labs.