Morphology is the study of the structure and formation of words in a language, focusing on how words are constructed from smaller units called morphemes. Morphemes are the smallest meaningful units of a language, with two main types: free morphemes that can stand alone as words, and bound morphemes that cannot stand alone and must be attached to other morphemes to convey meaning. Affixes are bound morphemes that modify a word's meaning or function, including prefixes, suffixes, and infixes. Inflection involves changing the form of a word to express grammatical categories, while derivation creates new words by adding affixes to a base word. Morphology helps understanding language structure and grammar by revealing how words are constructed and how their meanings can change through morphological processes.