A battery grip is an accessory for an SLR/DSLR, which permits the camera to hold multiple batteries to increase the battery lifespan of the camera, and adds a vertical grip with an additional shutter release, facilitating the shooting of portrait photography. It often fastens to the camera body through the camera's own battery compartment and offers a cassette to hold extra batteries to extend the battery life-span for the camera. Most battery grips also come with a second cassette permitting the cameraman to shoot using multiple AA batteries.

What actually is a battery grip?
Many enormous brand SLR camera producers including Nikon and Canon now give photographers the choice of an add-on handgrip/battery grip. With a camera attached, it makes the set-up look more squares-shaped than oblong. Aside from looking bigger and more provoking, there are more benefits to using a battery grip.

Advantages of camera battery grips
Battery grips make it less complicated for those with bigger hands to hold the camera. In a number of cases even those with smaller hands will find it of use when holding the camera in a horizontal position.

Many battery grips nowadays are produced to hold more than one battery. For instance, the battery grip for Canon's EOS 400D (Digital Rebel XT/Kiss), holds 2 batteries. Many photographers will recall a considerable number of instances when they have been half way through a shot, when they find the camera locks up because of a low battery. By the time they have modified the power supply, the shot is long gone. Adding a grip that holds two batteries to your set will help unravel this difficulty. The camera will not lock up till both the batteries are low. Some battery grips have an extra virtue of weather protection. Many photographers believe they extend the battery lifespan in cold conditions when typically they run down faster.