Why is it necessary to have the film in a lightproof cassette?

A lightproof cassette is essential for film storage and handling because it prevents exposure to light, which can fog or ruin undeveloped film. Light-sensitive emulsions on the film are vulnerable to any light exposure, leading to unwanted images or loss of detail. By using a lightproof cassette, photographers can safely load and unload film in various lighting conditions without compromising the quality of their images.