Flash is primarily suited to macro photography. The close subject distances inherent in macro photography require narrow aperture openings to obtain adequate DOF (Depth of Field). These narrow openings require lots of light or very slow shutter speeds. Slow shutter speeds dictate the use of a very stable tripod or a motionless subject.
The other option, lots of light, is generally provided by a flash. The burst of light provided by a flash is generally fast enough (provided that any ambient light is overcome) to freeze both subject and camera motion.
Although there are many ways to utilize a flash for macro photography lighting, I don’t think any are as easy to use and as flexible as the Canon Macro TwinLite MT-24EX Flash. The twin heads can be moved around the ring independently and the heads can swivel in and out.