Nikon SB-700 Speedlight buying (External Flash)

Product Name: Nikon SB-700 Speedlight buying (External Flash)
(Nikon USA says:) Optimized for use with Nikon's Creative Lighting System (CLS), the SB-700 Speedlight is equipped with Nikon's precision i-TTL (Intelligent Through-The-Lens) flash control to deliver precise flash exposures and seamless fill-flash performance—even in challenging lighting situations. Immediately before the main flash goes off, the SB-700 fires a series of monitor pre-flashes, which convey Information about the scene's lighting to the camera. i-TTL then automatically balances the output of buying the Speedlight and the scene's ambient light.