Bleeding, technically known as hemorrhaging or haemorrhaging (see American and British spelling differences), is the loss of blood or blood escape from the circulatory system. Bleeding can occur internally, where blood leaks from blood vessels inside the body, or externally, either through a natural opening such as the vagina, mouth, nose, ear or anus, or through a break in the skin. Desanguination is a massive blood loss, and the complete loss of blood is referred to as exsanguination. Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties, and blood donation typically takes 8–10% of the donor's blood volume.

Hemorrhaging is broken down into four classes by the American College of Surgeons' Advanced Trauma Life Support (ATLS).

This system is basically the same as used in the staging of hypovolemic shock.

Individuals in excellent physical and cardiovascular shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital signs, while having poor peripheral perfusion. Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate, and may take medications such as betablockers that can potentially blunt the cardiovascular response. Care must be taken in the assessment of these patients.

Christopher Adam "Chris" Daughtry (born December 26, 1979) is an American musician best known as the lead vocalist and rhythm guitarist for the rock band Daughtry and as the fourth-place contestant on the fifth season of American Idol, the competition that he was eliminated from on May 10, 2006. After his elimination from Idol, he was given a record deal by RCA Records and formed a band called Daughtry. Their self-titled debut album became the fastest selling debut rock album in history, selling more than one million copies after just five weeks of release. The album was recorded before the band was officially formed, making Chris Daughtry the only official member present on the album. This led some to believe mistakenly that the band Daughtry is Chris Daughtry's solo project.

In its ninth week of release, Daughtry reached number one on the Billboard charts. Chris Daughtry is now the third most successful American Idol contestant in terms of record sales, behind only Kelly Clarkson and Carrie Underwood, who both won their respective seasons. At the 50th Grammy Awards, the band was nominated for Best Rock Song for the single "It's Not Over".

Toryn Green (born November 3, 1975) is the vocalist for hard-rock band For The Taking, and the former vocalist for Fuel. He also was the touring lead vocalist for the band Apocalyptica and performed in both of its 2008 US Worlds Collide Tours. The first For The Taking EP, entitled Blackout, was released in September 2011, with songs such as "Lie to Me".

Toryn was raised in Alaska, where he graduated from Colony High School in 1994. Growing up Green was inspired by bands like Stone Temple Pilots, Bush, Metallica, Tool, and Fuel. His father was very musical and he says he gained lots of inspiration through him. He used to sing with his father since he was a small boy, but his first public solo performance was at Alaska State Fair. He moved to California in October 1998 to pursue career in music.

Green took his songwriting to the stage in his first band "Patience Worth", with band members Orion Rainz, Ryan Giles, and Cesar Guevarra. They recorded a few songs together, but eventually the band was moving in different creative directions. With his next band, Southern California rock band Something To Burn, Green won a Rock Beijing Global competition and was invited to play to thousands at the Midi festival in Beijing in October 2005. Two months later they represented America in the Worldwide Battle of the Bands held in Hong Kong. With STB Green recorded an EP entitled The Incinerator, which was released in April 2006.