This document discusses the differences between countable and uncountable nouns in English. It notes that countable nouns can be counted and can be singular or plural, while uncountable nouns cannot be counted and are only used in the singular form. It provides examples for how to use articles, verbs, quantifiers, and pluralization differently with countable versus uncountable nouns. It also notes some nouns can be either countable or uncountable depending on whether they refer to individual items or mass quantities.