[1] Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a puncture in the skin.

[3] The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery.

The discussion here is limited to the common practical aspects of blood clot formation which manifest as bleeding.

One of the most common causes of increased bleeding risk is exposure to nonsteroidal anti-inflammatory drugs (NSAIDs).

It is caused by a deficiency or abnormal function of the "Von Willebrand" factor, which is involved in platelet activation.

Vitamin K is required for the production of the clotting factors, II, VII, IX, and X in the liver.

[6] Dioxaborolane chemistry enables radioactive fluoride (18F) labeling of red blood cells, which allows for positron emission tomography (PET) imaging of intracerebral hemorrhages.

[7] Hemorrhaging is broken down into four classes by the American College of Surgeons' advanced trauma life support (ATLS).

These patients may look deceptively stable, with minimal derangements in vital signs, while having poor peripheral perfusion.

"[9] The World Health Organization made a standardized grading scale to measure the severity of bleeding.

[12] Anticoagulant medications may need to be discontinued and possibly reversed in patients with clinically significant bleeding.

[14] The use of cyanoacrylate glue to prevent bleeding and seal battle wounds was designed and first used in the Vietnam War.

[16] The word "Haemorrhage" (or hæmorrhage; using the æ ligature) comes from Latin haemorrhagia, from Ancient Greek αἱμορραγία (haimorrhagía, "a violent bleeding"), from αἱμορραγής (haimorrhagḗs, "bleeding violently"), from αἷμα (haîma, "blood") + -ραγία (-ragía), from ῥηγνύναι (rhēgnúnai, "to break, burst").