Noun: Definition
A noun is a word that names a person, place, thing, or idea. It serves as the subject or object in a sentence, playing a crucial role in communication.

Types of Nouns
- Common Nouns: General names for a class of objects (e.g., city, car).
- Proper Nouns: Specific names of people, places, or organizations (e.g., Delhi, Einstein).
- Collective Nouns: Names for a group of people or things (e.g., team, flock).
- Abstract Nouns: Names for concepts or ideas that cannot be touched (e.g., love, freedom).
- Concrete Nouns: Names for things that can be perceived by the senses (e.g., apple, chair).

Features of Nouns
- Number: Nouns can be singular (one) or plural (more than one).
- Gender: Nouns can be masculine, feminine, or neuter, affecting agreement in language.
- Case: Nouns can show possession (e.g., John's book) or indicate the role in a sentence (subject, object).
- Countability: Nouns can be countable (e.g., book/books) or uncountable (e.g., water, information).

Usage of Nouns in Sentences
Nouns can act as:
- Subjects: The doer of the action (e.g., The dog barks).
- Objects: The receiver of the action (e.g., She reads a book).
- Predicates: Nouns can also serve as complements (e.g., He is a teacher).
Understanding nouns and their features is essential for mastering grammar and enhancing language skills.