What are the important functions of film graininess?

Film particles are by-products of chemical reactions, and their functions in photography are as follows:

1. The overall graininess brings uniform texture to the image.

2. Create a sense of looseness and vicissitudes.

Fade down details

Weaken color

5. The mechanism and texture of making the whole or part (local parts here, such as black and white photos, will be obviously reflected in the black parts if white dry spots are produced)