Proper Nouns name specific people or places and take capital letters (Ranchi, Jharkhand, Tagore). Common Nouns name general classes (river, city, student). Collective Nouns name groups (flock of birds, bouquet of flowers). Abstract Nouns name qualities, concepts, or states (freedom, honesty, fear). Countable Nouns have plurals and take numbers; Uncountable Nouns (water, sugar, advice, knowledge) do not take plural '-s' or 'a/an'.