What's an external mic?

I'm planning on buying a NIkon D3100 DSLR camera and all the reviews say one con about the camera is it doesn't have an external mic. What does that mean?

It doesn't have one, not that you would need one for a digital still camera. Just use the internal one. If you want a camera that's actually good for video than get a real video camera, not a still camera that does video.

Here is a link to a dSLR being used as a video camera. Notice the gray fluffy thing mounted on top of the camera. That is an external microphone.

It does have an INTERNAL mic, as for a external mic, it's a microphone you can connect to the camera. As for the D3100, it doesn't have input for external mic, but the next one on the line, D5100, has input for external mic, and it's a better and newer camera, and it isn't much more expensive.

Check its review here.

http://www.dpreview.com/...ikond5100/