Product descriptions list white (shiro) miso as typically aged about 3 months and red (aka) miso as typically aged about 6 months. (Exact aging can vary by producer.)
The product descriptions consistently list soybeans, rice (koji or cultured rice), and salt as the core ingredients used in miso fermentation.
For paste-style miso, add it near the end of cooking and avoid boiling so the cultures and delicate flavors aren’t destroyed. Instant or cup-style miso soups are prepared by adding hot water and stirring until rehydrated.
Two common types are white (shiro) and red (aka) miso. White/shiro is aged for a shorter time, is lighter in color, milder in flavor, and generally has a lower perceived saltiness; red/aka is aged longer, darker, and develops a stronger, more robust flavor.
Miso is used for miso soup, marinades (e.g., for fish), glazes, sautés, ramen, pickles, dressings, and sauces for noodles or salads.