Tends to be very grainy. Doubling the film speed represents a 1 stop increase in film sensitivity, or a 1 stop decrease in need for light. Doubling the film speed means choosing a film that is 1 stop faster. Faster films allow shooting in low light situations with faster shutter speeds or without recourse to a tripod. Increasing Graininess of Film Grain refers to the apparent size of the clumps of light sensitive silver on the film.
Grain affects the appearance of sharpness of the resulting print.
The more grainy the film the less sharp large prints will appear. This means that from the darkest area that still retains some detail to the lightest area that still retains detail, there is about a 5 stop range. Objects outside the range will be produced on the negative as featureless dark or black areas or as featureless white areas. Typically, the ISO number of the film will be set with the film speed dial or automatically if your camera reads the DX code on the film cannister. The new film speed is referred to as the Exposure Index.