The body communicates internally via electrical impulses through nerves and their tell-all components, neurons. Those communications might be transmitting messages such as "ouch, that's hot," or "then move your finger away from the heat, dummy," or "um-m-m-m, donuts."

Nerves are the main conduits for information. The nerves are comprised of - among other things - neurons. The neurons are 'excitable' cells. What excites them is data. When excited (which is most of the time) neurons gossip among themselves, thus passing on that data. Most normal gossip flows to or from the brain in a reasonably orderly fashion.

Neurons also exist throughout the brain. There they perform the same function: move data.

Whereever located, and whatever their function, neurons exchange information by exchanging chemicals - somewhat like trading spit to say "I want to get into your pants." One cell's neurotransmitters release chemicals that are received by another cell's neuroreceptors. The specifics of the chemicals determine the message conveyed (and the message received).

Nerve impulses to and from the brain travel as fast as 170 miles per hour. Ever wonder how you can react so fast to things around you or why that stubbed toe hurts right away? It’s due to the super-speedy movement of nerve impulses from your brain to the rest of your body and vice versa, bringing reactions at the speed of a high powered luxury sports car.

Information travels at different speeds within different types of neurons. Not all neurons are the same. There are a few different types within the body. Transmission along these different kinds can be as slow as 0.5 meters/sec or as fast as 120 meters/sec.

Context check:

120 meters/sec = 268.4 miles/hour
0.5 meters/sec = 1.1 miles/hour ¹
170 miles/hour = roughly, um, 170 miles per hour

¹ This lower figured has been measured in in the brains of Homer Simpson, his barroom friends, and people who watch Faux-Fake-Phony-Fox News.

Sources:

1. Bootstrapper.
2. Me.
3. Watching Faux-Fake-Phony-Fox News viewers in action.