This document discusses different types of morphemes and how they combine to form words. It defines morphemes as the smallest units of meaning in a language. There are two main types of morphemes - lexical morphemes which have their own meaning and functional morphemes which alter grammar. Derivational morphemes add prefixes or suffixes to create new words with new meanings, while inflectional morphemes change word forms and functions through affixes like number, possession, and tense. Words are formed through the process of affixation by adding prefixes, suffixes, circumfixes, or infixes to morphemes.