Condenser - is a fragile microphone, and commonly needs power, such as phantom power, in order to work.   It has a wide frequency and dynamic range, making it a choice pick for many applications.

Dynamic - is the most durable of microphones. It resists moisture well, and no power is needed for it to work.   Great for live sound and recording loud sound sources.

Ribbon - is a form of Dynamic microphone, which uses a thin aluminum ribbon stretched between the poles of a magnet, as its membrane to convert sound into an electrical signal.   This microphone is the most fragile, damaged easily by a gust of wind.   It is typically bidirectional.

Polar Patterns

Omnidirectional - These microphones react to sound evenly from all directions.

Cardioid - is the most common of the unidirectional polar patterns.   It rejects sound from the rear and picks up sound from in front.

Super-cardioid - has a slightly tighter front pickup area and lets in a small amount of sound from the rear.

Hyper-cardioid - another step further...  Even tighter front pickup area and an area in the rear which picks up sound.

Figure 8 or bi-directional - picks up sound from both the front and back, and not so much from the sides.

Shotgun - A shotgun microphone is similar to a microphone with a hyper-cardioid polar pattern, but shotgun microphones have longer bodies with many defusing slits, when the sound reaches the capsule at the end, there is almost no sound picked up from behind or from the side.

References - Wikipedia - http://en.wikipedia.org/wiki/Microphone