Uncountable nouns are nouns that cannot be counted individually. They represent things that are seen as a whole or mass, such as water, sand, or information. These nouns do not have a plural form and are often used with singular verbs. For example, we say "The water is cold," not "The waters are cold." Common categories of uncountable nouns include substances, abstract concepts, and collective categories. Examples include music, happiness, and furniture. When using uncountable nouns, we often quantify them with words like "some," "much," or "a little," rather than using numbers directly.