Zombie agility has improved by literal leaps and bounds since the days of Romero's shambling hordes. Yup, it's probably time to start worrying.

Just The Facts

  1. Zombies are reanimated corpses.
  2. If a zombie bites you, you become one.
  3. The only way to kill a zombie is to damage its brain or remove its head.
  4. There is no cure for zombiism.

What is a Zombie and Where do Zombies Come From?

Zombies are the dead brought back to life. They retain only the most primal instincts, such as going to the mall and eating. They rarely retain the ability to speak. Zombies feed on living flesh, particularly human brains. Were it not for this last trait, zombies would be indistinguishable from the average American teenager.

There are two main theories on the origin of zombies:

1. Voodoo. A Voodoo priestess curses your soul and when you die, you return as a zombie. It's unclear what the downside of the curse is.
2. The zombie virus. Some believe that zombies can be created by a sort of "zombie virus." The virus can sometimes be airborne or transferred through bodily fluids, such as biting or kissing.
If a zombie bites you, you become a zombie. If you bite a zombie, you immediately go to metal heaven where you spend eternity playing flaming guitars with Jimi Hendrix and Prince. The zombie's first instinct is to feed on living flesh, so this is the most common and fastest method of spreading zombiism.

The Quickening of Zombies

Zombies have taken a prominent part in popular culture thanks to two men: George A. Romero and Michael Jackson.
George Romero at Comic Con International 2007
In 1968, Romero released Night of the Living Dead. This movie was followed up 10 years later by Dawn of the Dead, which picked up where the previous movie left off. At dawn. The Romero series focuses on zombies attacking a city. Most of the citizens are turned and attack outposts of hiding humans. Sexual tension ensues.
In 1983, Michael Jackson released the most popular music video of all time, Thriller. In a sad, prophetic fashion, Michael Jackson, for an unknown reason, undergoes a physical transformation turning into a pale-skinned creature we have come to recognize as a zombie, and begins a choreographed dance of the dead.
The 80s saw a boom in horror movies and the zombies continued to ride the Romero/Jackson wave. The third movie in Romero's series came out in 1985, Day of the Dead (which picked up where Dawn of the Dead left off), as did Return of the Living Dead. Return of the Living Dead was not part of Romero's series, but referenced Night of the Living Dead and had the same premise. Return of the Living Dead taught us one more important thing about zombies: they still look good topless. Likewise, we learned that a nipple flash can be a substitute for a plot or for special effects. Flash both, and you can save a lot of time and money.
The next significant event in zombie pop culture came in 1996 when Resident Evil came to Playstation.
Resident Evil, the first "survival horror" game, introduced the dog zombie and the plant zombie. However, zombies remained, for the most part, slow-moving, flesh-eating monsters. While scary, these zombies provided two methods of escape: walking away with a brisk pace or standing there for a little while to think of a better plan. The Resident Evil movie came out in 2002. It fixed the main flaw that afflicted the video game: no hot chick in a designer dress who killed zombies by jump kicking them.
It wasn't until later that year that we were introduced to the fast-moving zombie for the first time in 28 Days Later. Basically, zombies take over England and kill everyone in the city, except one guy, who was asleep when the attack happened. Then, he escapes to a military base and, naturally, sexual tension ensues. The Dawn of the Dead 2004 remake followed the fast-zombie model. We also learned that if you are locked in a building with bulletproof doors, food, hot girls that want to have sex with you while you record it, DO NOT build an armored bus and try to go somewhere else.
2004 turned out to be one of the most significant years in zombie films. Not only did we see Dawn of the Dead, we also got Shaun of the Dead, quite possibly one of the greatest movies ever made [in England]. Shaun of the Dead was the first romantic comedy about zombies. It parodied Dawn of the Dead, 28 Days Later and just about every zombie movie ever made. It seemed like zombie movies were just getting better and better until September 2004, when the sequel to Resident Evil, Resident Evil: Apocalypse came out. The movie poster featured a naked woman walking through a graveyard with a gun:
Unfortunately, the movie did not feature a naked woman walking through a graveyard with a gun.
Romero, after a long break, came back in 2005 with Land of the Dead, about a post-apocalyptic society where zombies rule the land and the living are hunkered down in fortress of a city.
2007 saw even more zombie movies with 28 Weeks Later, the sequel to 28 Days Later, and the third Resident Evil movie, Resident Evil: Extinction. In 28 Weeks Later, the Americans show up to save Britain 28 weeks after the zombie outbreak. That's right, about six months later. All British people who have not died of starvation or turned into a zombie are rounded up and put into a camp. The Americans bring a zombie into the camp, bomb the city and fly away in the jets they rode in on. USA! USA!

Ein! Zwei! Die!

January 2009 saw the release of Dead Snow, a Norwegian movie about a group of young attractive teenage friends who go skiing in the mountains in Norway. Dead Snow was shown at the Sundance Film Festival, so only like 112 people have seen it so far, but from the trailer (which is in Norwegian), here's a basic plot summary: The teenagers start out by having fun and laughing. Then, they go into a cabin and meet an old man. Danger. Treasure. Gold. Nazi zombies reanimate and rise from the snow in full uniform. There's some arguing or something. Some chick screams. Chainsaws, blunt weapons, knives. Zombies get messed up. So, pretty much, it looks like the greatest movie ever made.

The Motorcycle-Riding Machine Gun Zombie

Resident Evil 5 came out in March 2009 and introduced us to new breeds of zombie: the motorcycle-riding zombie and the machine gun zombie. RE 5 takes place in Africa. Chris Redfield, who was infected with the anabolic steroids virus, teams up with native African and freaking hot sidekick, Sheva. Sheva can be either controlled by a second player or the computer. The game play is realistic, except that all of the African villagers/zombies have machetes, clubs, Molotov cocktails, crossbows or assault weapons. So it's not at all like the real Africa. In RE 5, the zombies are a bit more intelligent than in the previous versions and have mastered the use of heavy artillery, driving big semi trucks into you, chasing you on dirt bikes and sniping at you from afar with fully-automatic weapons. Luckily, just like in real life, shooting a zombie will likely turn its body into gold or ammo. You can use the gold or artifacts that you steal from the treasure chests that Africans have in their huts to buy things or upgrade your weapons.

Stopping Zombies

Don't let that emo look or that human-looking belly stop you. These guys will mess you up.
Zombies can be killed by either shooting them in the head or removing the brain. Popular weapons against zombies include: handguns, chainsaws, shotguns, knives and tetherball poles.

Surviving the Zombie Apocalypse

There are two things you need to know about the zombie apocalypse: 1) It's completely possible (see: 5 Scientific Reasons a Zombie Apocalypse Could Actually Happen). 2) There has never been a scenario where a zombie outbreak has resulted in anything less than the absolute end of the world. And don't forget to have your backup plan for when they do come: What's Your Zombie Contingency Plan? 11 Practical Strategies.
Recognizing the warning signs is vital. Cracked addressed that too (see : 6 Signs You Are About to Be Attacked by Zombies).
If you see papers strewn about and burned cars, and you are not in Detroit or Philadelphia, RUN. Zombies can't be far behind. This is also the best course of action if you are in Detroit or Philadelphia.