I need to describe a bit about the body first. Signals to and from the brain travel down nerves - at least the type of signal I'm talking about. These include commands to move as well as reports of hot/cold, pain, touch, taste, smell, sight, and sound.

The way nerves work is by conducting small currents of electricity from your brain to wherever on the body - Let's use the hand as an example. If you want to close your hand, a signal is sent from your brain to your hand that causes the muscles to contract and your hand closes. That signal is sent through nerves. Your spinal cord is one big nerve and that's why people that break their neck are often paralyzed - because the signal can no longer be transmitted to close the hand. They often die because the signal from the brain to pump the heart can't be transmitted either and their heart stops beating properly. Nerves are like power cords to and from your brain, which makes them the path of least resistance.

I've heard many times that it isn't the volts that will kill you - it's the amps. Actually, it's a combination of both. The volts describe how hot the electrons are while the amps describes how many electrons there are. Think of it like pebbles rolling down a mountain. The volts tell you how high they are when they start to roll, the amps tells you how many pebbles are rolling. One pebble rolling down Everest isn't going to even hurt you, but an avalanche of pebbles on a small hill can still hurt you badly.

Another common misconception is the idea of a path of least resistance. Electrons would like to travel down a path of least resistance, but will take any path they can. If you grab onto a power line with both hands, most of the electricity will still travel through the line. Only a tiny fraction of that electricity will flow through you. Compared to metal, human flesh is a poor conductor. However, compared to air or rubber, human flesh is a great conductor, and nerves will be the path of least resistance.

When you stick your finger in a light socket, that electricity will travel through you instead, your nerves in particular. That's why when electricity travels through you, your muscles start behaving funny, the contact point of the electricity hurts like hell, and your heart can sometimes stop (or if you're in the ER and your heart has already stopped, they'll use electricity to start it again.).

When a signal is sent to your brain, only a fraction of your nerves are transmitting at once. Think of it like thousands of tiny cords bound together to make a big cord where the big cord is the part that travels from your hand to your brain. Only a fraction of the tiny cords are transmitting at any given moment. That's why there are different levels of pain - the more pain you're feeling, the more nerve endings are transmitting. That's why electricity hurts so bad - it causes a lot of nerve endings to transmit at once.

How many people do you know have been killed by electricity? I've met three people in my life that I know of that have been struck by lightning. My little brother shocked himself in an outlet before. My big brother grabbed a hot wire and did this funny dance that I still laugh about today. And we all have dragged our socks on the carpet and touched someone to shock them. We all have been electrocuted on some level or another. And I don't know anyone that actually died from electrocution.

Nowadays electricity has been engineered to help save idiots such as myself (I electrocuted myself five times on the same television before I figured out it wasn't worth repairing). There are a few properties I must describe before it will make sense.

Capacitance. Capacitance is how many electrons you can hold before you need to start getting getting rid of them. When you rub your socks on the floor, it will only pick up so much charge - you can't build up an infinite amount.

Alternating Current. AC is more efficient than Direct Current (DC), which is why all long-range transmission lines are AC. Most household appliances run on AC. Anything that has a circuit-board in it runs on DC and must have a converter before it can operate. But vacuums, lights, toasters, ovens, and heaters all run on AC. AC is where the voltage fluctuates in the line. DC is where the voltage remains constant in the line. In America, all major AC systems are 110 volts that fluctuate 60 times per second. In Britain it's 120 and 50 times per second I believe (could be wrong).

Conductor. A conductor is different than a capacitor. A conductor allows electrocity to flow through it while a capacitor stores up the energy inside it. Some objects act like both - helicopters on line repairs will conduct electricity heading into the chopper until it reaches its limit, then when the voltage drops in the line the chopper will dump that electricity back into the line. This happens sixty times per second so it looks like a constant flow of electricity. Consider the video below.

In the old days, the voltage in AC used to go from 55 positive volts to 55 negative volts, sweeping 110 volts in between. This meant that electricity flowed out of a wire and then into the wire 60 times per second. If you stuck your finger in that socket, the electricity would push you away but before you could move far enough away the electricity would suck you back in again. Your own commands for motion would be muted by the electricity from the wall frying your nerves. Thus, people could not pull their fingers out of sockets or get their hands to let go of power lines. They would get electrocuted until they died.

Engineers figured out how to still have AC but now have it all positive voltage. This means that electricity will only flow from you back into the wire if you are holding a charge greater in voltage than the wire. Usually you conduct charge more than store it, so whatever electricity was pushed into you originally ended up in the floor. You can say that you maintain a zero charge and never have a voltage higher than the wire. When you stick your finger in a modern socket the socket will never have a negative charge, meaning that electricity will never flow through you back into the socket. Thus, you will never get sucked back in - you will only get blown away from the socket. The act of blowing you away from the socket still classifies as electrocution and it will either really wake you up or it will knock you out. But it will not keep you stuck to the socket and continue to electrocute you. Thus, engineers have greatly increased the survival rate of electrocution.

Now there's a catch to this story. If you make contact with both a positive wire and a neutral wire, your body will still conduct electricity at all times and not get blown away. That is what happened to my brother when he grabbed a small box that was positive on one side and neutral on the other - the electricity flowed only through his hand and not the rest of his body. It still made his nerves send pain signals to his brain and woke him up. It still left him motor functions to his legs so he was able to yank his hand off the box, but he had trouble getting his fingers to let go. The noise he made was the funniest noise I ever heard. This special case of touching two conductors at once is not something you see often. When you stick your finger in a power socket you usually can only touch one conductor at a time.

P.S. Lightning is DC.