Sodium hydrosulfite, also known as sodium dithionite, has a wide range of uses in various industries. Here are some of the major applications of sodium hydrosulfite:

1. Textile industry: Sodium hydrosulfite is widely used in the textile industry for bleaching and reducing agents. It is used to remove color from natural and synthetic fibers, especially for cotton, wool, and silk.
2. Pulp and paper industry: Sodium hydrosulfite is used to bleach wood pulp in the paper industry, which results in bright white paper.
3. Water treatment: Sodium hydrosulfite is used as a dechlorinating agent in water treatment plants. It can reduce chlorine levels in water, making it safe for drinking.
4. Food industry: Sodium hydrosulfite is used as a food additive to preserve food color and flavor. It is also used in the production of various food products such as canned fruits and vegetables, wine, beer, and baked goods.
5. Chemical industry: Sodium hydrosulfite is used as a reducing agent in various chemical reactions, such as the reduction of nitro compounds and the conversion of aromatic amines to hydrazines.
6. Photography: Sodium hydrosulfite is used as a photographic developer, which is an essential component in developing black and white films and prints.

Overall, sodium hydrosulfite is a versatile and important chemical that finds use in many different industries.