Countable and uncountable nouns can be distinguished based on whether they can be counted or not. Countable nouns refer to things that can be counted, like pens, dogs, bottles. They can be singular or plural. Uncountable nouns refer to substances or abstract concepts that cannot be counted, like milk, furniture, happiness. Uncountable nouns are usually singular. Both countable and uncountable nouns can be used with quantifiers like some, any, a little, much. Some nouns can be both countable and uncountable depending on meaning. A partitive structure using a measure word is used to quantify uncountable nouns.