Inflectional affixes are grammatical morphemes added to a word to express different grammatical categories such as tense, mood, voice, aspect, person, number, gender, and case. Unlike derivational affixes, which create new words, inflectional affixes modify existing words to convey specific meanings. For example, adding -s to the noun cat forms the plural cats. In English, common inflectional affixes include -ed for past tense, as in walk becoming walked, and -ing for present participle, as in run becoming running. These affixes help clarify the role of a word in a sentence, enhancing communication and understanding.