Excerpt: You are looking at one of the most popular DSLR accessories available - a shoe-mount flash. The Canon Speedlite 430EX II Flash, at the time of this review, is Canon's middle child of standard Speedlite flashes. It contains a big amount of functionality , power and style in a modestly priced and sized body.
Excerpt: Why? Why use an external flash? The answer may be obvious to owners of camera bodies without a built-in flash, but not so clear to those using bodies with a built-in flash. The built-in flash is great for fill flash to light the shaded areas (such as people's eyes) in a pictures. To use fill flash, set your exposure for the ambient light, then dial in -1 to -2 EV FEC (Flash Exposure Compensation).
Excerpt: Photography is about creating images with light. For indoor, night, fill light, or certain special effects, using electronic flashes to generate light becomes an important component in modern photography. Canon flash units are called “Speedlites” by Canon. There are currently three shoe mount Speedlites (220EX, 430EX II and 580EX II) as well as two specialty macro flash systems (MR-14EX and MT24EX ).