What type of Shutter Release works with a Nikon D3100?

I'm looking to buy a shutter release for my Nikon. I know Nikon makes a few different types of wired shutter releases so I need to know which ones work with a D3100.

If they're all compatible with my camera, could someone explain why there are different types then?

Have you ever looked at your manual and/or the Nikon website?

I just looked it up for you and learned that your camera needs a Remote Cord MC-DC2 as shown here:
http://imaging.nikon.com/...lity01.htm

Now you know what you need and you can go shopping: http://www.amazon.com/...zon.com/s/

You can get different types of releases, but the plug has to fit unless it is a cordless variety.

This is the one you want.

http://www.amazon.com/...001F6TXME/

Here's a review from someone who used it to for the D3100.

"You must have this for taking long exposure and bulb shots over 30 seconds. Great for astrophotography. It's also useful when using a tripod. Plug and play. Works perfectly with D3100."

By the way it's known as a remote. The shutter release is inside the camera.

The remote that will work with your camera is listed on page 177 of your manual. Download your manual from Nikon if you need one.

Not all of them are compatible with your camera.

For some reason, the D3000 was an IR remote, the D3100 was a cable remote, and the D3200 has both.

However, skilled photographers generally prefer the wired (cable) remotes as they are not as finicky as the IR remotes; and they can be used to attach accessories, such as intervalometers and camera triggers to the camera - IR remotes can't do that.

And wired remotes are "faster". Their response time is in the microsecond range, while IR remotes are typically in the millisecond range. This is not an issue for most situations, but for example; a lightning trigger - the lightning event typically only lasts a few milliseconds - too fast for a IR based camera trigger to respond.

Wired remotes - even the most cheap 3rd party ones - typically have a lock button for BULB use (great for fireworks, light painting, etc).

And if you want a wireless remote, you can buy a RF remote that has a 100~200ft range. They come with a transmitter and receiver - the receiver connects to the wired remote port of your camera. You do not have that range with an IR remote (which is perhaps 10ft at most).

However, most cameras have unique connectors for the remote, depending on the brand and model. You need a MC-DC2 compatible connector. As long as you buy that version, it will work with your camera.