This document discusses inflection and its forms. It defines inflection as variation in the form of a word, typically by means of an affix, that expresses a grammatical contrast. It explains that words have lexemes, word forms, and grammatical words. Regular inflection follows predictable rules, while irregular inflection does not. It provides examples of regular and irregular plural nouns. Finally, it discusses the three forms of countable nouns: singular, plural, and singular-plural.