While rendering stills will allow you to view and save the image from the render buffer when it's complete, animations are a series of images, or frames, and are automatically saved directly out to disk after being rendered.
Traditional still scene rendering usually involves lamps, spots, etc. But GI is a radiosity technique that allows you to light a scene from 360 degrees without a single lamp. This gives your scene more of a stylistic look.
One of the keys for the rendering of a good scene relies on the appropriate choice of the material properties of objects within it. You can have the most beautiful, the most original and the finest models of the world, poorly managed materials can nothing but spoil your scene.
It is important to understand how work the many Material Buttons in order to use them the best possible way.