In everyday life if something happens, you would control the bleeding as best as you could, call 911 or rush the person to the nearest hospital and they would be looked after by professionals. What about in a disaster situation and you are now in survival mode, not knowing when or if help will reach you and your victim.
Any kind of bleeding should be controlled as quickly as possible. If you lose 1 liter of blood you'll have shock like symptoms, 2 liters will put you in extreme shock and 3 liters of blood loss is normally fatal.
Shock will happen when the brain or heart are deprived of oxygen due to a problem affecting the circulation system such as a cut artery. Signs of shock are, the person will look really pale, they will be cold and have clammy skin, their breathing will be weak and rapid and they'll be sighing or yawning a lot. To treat shock you should have the person lie down, raise and support their legs, loosen any tight clothing they may be wearing and keep them as warm as you can.
The main blood vessels are called ARTERIES, they carry blood from the heart to all parts of the body. When the arteries get cut the blood will be a bright red and will be spurting out with each beat of the heart, because it's being literally pumped out of the body, it would not take long to lose a lot of blood in a hurry. This type of cut must be controlled as quickly as possible with direct pressure over the wound, if the wound continues to bleed, you may need to apply a tourniquet. Only use a tourniquet if you really have to, and for no longer than necessary, as this can damage the surrounding tissues and create more problems. A tourniquet should be released at least every 15 minutes to allow circulation to return to the remainder of the limb. If this is not done, chances are the limb may have to be amputated later on. I guess common sense would tell you to never use a tourniquet around a persons neck, if your going to choke him, you might as well let him bleed out. Having said that, you must be careful applying pressure to the arteries on the neck for too long as you could render the victim unconscious.
If the wound is on the lower part of the body or their arms, have the person lay down and elevate where the wound is, so that it is higher than the heart, this will slow the blood flow to the wound, plus if the person happens to go into shock, you want them laying down anyways. If the wound is on the upper part of the body, have them sit up with some kind of support and watch that they do not pass out. Always try to keep the wound elevated higher then the heart.
In a survival situation chances are you may not have pressure type dressings with you, this is where you're going to improvise, rip up a shirt, blouse or tee shirt for dressings and tourniquets. You want the pressure dressing fairly thick and big enough to cover the wound completely, chances are the dressing is going to get soaked in blood, but that's okay, if it does put another dressing on top of the first, don't take it off unless it's still coming out as fast as when you applied the dressing. You need to slow down the bleeding in order for the blood to coagulate. The first step for the wound to heal is for the blood to clot.
Other cut blood vessels like the veins and the capillary, are easier to control then the main arteries. With the veins the blood will be a dark red to a bluish color, this is called Venous Blood, blood that is returning back to the heart. The capillary are small blood vessels that connect the arteries to the veins and is probably the most common type of bleeding, as you would get these from any minor cuts and scrapes, it is also the easiest to control, usually with just a band aid.
Pictured below is applying a pressure dressing and below that is how to apply a tourniquet.