Seaweeds are a type of marine plant that grow in oceans and other bodies of saltwater. They are classified into three main groups: green algae, brown algae, and red algae. Seaweeds play a crucial role in marine ecosystems, providing habitat and food for various marine organisms. These organisms are rich in nutrients and are often used in human diets, particularly in Asian cuisine. Seaweeds can also be processed into products like agar, carrageenan, and nori, which are used in food and other industries. Their ability to absorb carbon dioxide makes them important for environmental health.