There are four main types of sentences in English, each serving a different purpose. Declarative sentences state facts or opinions, such as “The sky is blue.” Interrogative sentences ask questions, like “What time is it?” Imperative sentences give commands or requests, for example, “Please close the door.” Exclamatory sentences express strong feelings or emotions, such as “What a beautiful day!” Understanding these sentence types helps in expressing thoughts clearly and effectively in both speech and writing.