Once you graduate from on-camera mics such as the Rode VideoMic Pro the next step is usually a real shotgun mic. Shotgun mics are popular due to their very directional nature. You can point them directly toward a subject to pick out their voice from the background noise. Or, they can be used in a more controlled, studio like environment to get very clean high quality recordings.
In this side-by-side comparison, Curtis Judd puts five shotgun microphones to the test. As well as comparing just how well each picks up sound, he performs an off-axis test. This helps to illustrate just how much environment noise away from your subject the microphones reject.