The document discusses several pieces of photography equipment:
1) A flashgun is used to provide extra light for photographs. It needs to be charged between flashes and can emit a bright light that washes out backgrounds. Looking directly at the flash can damage eyesight.
2) Colour gels are filters placed in front of lights to change their colour, and are used to manipulate how objects appear in photographs (e.g. red for danger). They can melt if left in front of lights for too long.
3) A constant light can be used for both photography and video. Colour gels can create effects when placed in front of it, and it can become very hot, so care is needed.