How exactly do lasers work? All we ever see is the light beam and thats what we immediately associate it with so how

Question: How exactly do lasers work? All we ever see is the light beam and thats what we immediately associate it with so how can there be lasers that cut through glass etc if its only a light beam? what realy is in a laser beam that makes it so powerful?
- Keywords:
  beam,
  glass,
  light
Asked by maia to Mike, Pip, Tianfu, Tim, Tom on 29 Jun 2012.
- Tim Stephens answered on 29 Jun 2012:
  
  A laser beam is a beam of light. Light is a type of energy, so a laser beam is a beam of energy. The reason that some lasers can cut through glass is that they are of a colour that is absorbed by glass – in fact they are usually ultraviolet lasers.
  
  When the beam is absorbed by glass, it transfers its energy to the glass, which causes it to melt.
- Tom Lister answered on 30 Jun 2012:
  
  Lots and lots of light in a small spot. You can set things on fire using a focused beam of sunlight, which is the same idea really.

Question: How exactly do lasers work? All we ever see is the light beam and thats what we immediately associate it with so how can there be lasers that cut through glass etc if its only a light beam? what realy is in a laser beam that makes it so powerful?