Film stock refers to the material used in traditional film cameras to capture images. It consists of a flexible strip coated with light-sensitive chemicals that react when exposed to light. Different types of film stock vary in sensitivity, color reproduction, and grain structure, affecting the final look of the film. There are two main categories of film stock: black-and-white and color. Each type can be further classified based on its speed, measured in ISO, which indicates how well it performs in different lighting conditions. Filmmakers choose specific film stocks to achieve desired artistic effects in their projects.