A quantifier is a word or phrase that indicates the quantity of a noun. It helps to specify how many or how much of something is being referred to. Common examples of quantifiers include words like "some," "many," "few," "all," and "none." They can be used with both countable nouns, such as apples or cars, and uncountable nouns, like water or sand. Quantifiers are essential in communication as they provide clarity and precision. For instance, saying "many students" gives a clearer idea than just saying "students." Understanding how to use quantifiers effectively can enhance both spoken and written language skills.