Before you pick up a gun—or introduce someone else to shooting—you must go over the four rules of gun safety. Though there are many safety rules in the firearms world, these four are the foundation to everything any of us will do with a gun.

The late Lt. Colonel Jeff Cooper wrote these four rules back in the 1970s. Cooper, having learned various firearms rules during his youth and through his Marine Corps career, thought there had to be a better way to present gun safety. He wanted rules that are succinct, firm, all-inclusive, and easy to remember. So he wrote down and fine-tuned what have become the four cardinal rules of gun safety. Most law-enforcement and military trainers have since adopted these rules, and many trainers now require students to memorize them.

At the Gunsite Academy, a privately run firearms-training facility in Paulden, Arizona that Cooper founded and where I instruct shooters, these rules are printed on the backs of instructors’ business cards, as well as on signs that appear everywhere from the lunch area to the bathrooms.

Despite this widespread repetition of the rules, however, I’ve come across many shooters—new and experienced—who aren’t quite sure what they mean, or worse, how they should be applied.

I tell my students that the four rules are the foundation to everything we do with a firearm. These rules should be applied everywhere, and all the time. Even if someone decides never to shoot again, I tell that shooter to internalize these rules, because lives depend on them. Here they are:

Rule 1: All firearms are always loaded.

This thought is where it all starts. Such a mindset allows us to avoid those unfortunate tales about someone who “thought it was unloaded,” or “was sure it had been emptied,” or “didn’t remember loading the gun.” It applies whether you’ve loaded or unloaded a firearm. All firearms are always loaded, so we must treat and handle them as such.

That means whenever we’re handing a firearm, we have to pay attention to it and to everything about it—where it is pointed, what is around us, what is near its trigger, what position its mechanical safety is in. The concept that a gun is always loaded requires us to be continuously aware of it–not just when we are loading a gun, nor just when we’re shooting it, but all the time. The person who lives by this rule avoids taking risks, is always mindful of his or her firearm, and is acutely aware of what damage it might do if discharged.

Rule 2: Never let the muzzle cover anything you’re not willing to destroy.

Once you’ve embraced Rule 1, Rule 2 comes naturally. More specific than “keeping the muzzle pointed in a safe direction,” Jeff Cooper’s second rule reminds us of what can happen if we don’t. The word “destroy” was chosen very carefully and despite some argument. Whether your gun is shooting pellets or a half-inch diameter bullet, the projectile from your firearm can permanently remove matter from whatever it penetrates. That matter will be destroyed, gone forever.

Again, this rule applies at all times—not just when you’re shooting, and not just when you’re holstering. Adhering to this rule will help you uphold the first rule when you are tempted to be lax, which is when and why most firearms accidents occur.

Rule 3: Keep your finger off the trigger until your sights are on target.

Sometimes called the “Golden Rule,” Rule 3 lets us know that the trigger should not be touched until and unless our sights are on target. At Gunsite, we add that a person’s trigger finger should lie straight alongside the firearm’s frame or receiver, as this prevents a finger from “accidentally” sliding in to the trigger area.

How can that happen, you ask? Easily. Humans have a “clutch reflex” –an involuntary muscular response that results in the fingers and thumb making clutching movements. The force of the clutching motion is more than enough to activate a trigger and to cause your gun to fire. One or more of these conditions may cause the reflex to occur:

  1. You are startled.

  2. You lose your balance.

  3. You use one hand (either your dominant or non-dominant hand) to grab, hold, or touch something, especially with some spontaneity.

Note that each of the three stimuli is fairly commonplace, and the reflex is exacerbated when we’re under some stress. The rule helps us counter the very real possibility that our hands will involuntarily move in a way that can cause a weapon to fire when we don’t want it to.

Rule 4: Be sure of your target.

This applies not only when actually firing the gun, but also when simply handling it. You must be absolutely sure that whatever you select as your target deserves to have your muzzle pointed at it. If there is any doubt, eliminate it. You must identify your target.

In addition, this rule carries with it the responsibility of all the paths of your projectiles. We usually add “and what’s all around it” to the end of the rule. That means that we recognize projectiles’ ability to pass completely through a target. We also understand that anything to the sides of a target may be at risk if they move into the path between the muzzle and the target. To put it another way: Be sure there are no unintended targets in your path!

As Colonel Cooper intended, the Four Safety Rules are simple, concise, and crafted with precision. And, as he envisioned, they are words to live by.