A noun is a word that names a person, place, thing, or idea. There are several types of nouns including proper nouns, which are capitalized names, and common nouns, which are not capitalized except at the beginning of a sentence. Nouns can also be concrete and name tangible things that can be perceived by the senses, or abstract and name intangible concepts. Nouns can be countable, with both singular and plural forms, or non-countable, only occurring in singular form. Nouns can also be made possessive to show ownership.