Morphology is the study of words and their internal structure and formation. It looks at morphemes, the smallest units of meaning, and how they combine to form words. There are two types of morphemes - free morphemes or lexemes which can stand alone as words, and bound morphemes or affixes which must be attached to other morphemes. Affixes that carry grammatical meaning are called inflectional affixes, while those with lexical meaning are used in word derivation to form new lexemes. Some major word formation processes in English are derivation, compounding, and conversion.