Speakers package thoughts into relatively independent units. A sentence is a grammatical structure that typically expresses a complete proposition, often defined as an independent clause or a coordinated set of clauses with conventional punctuation in writing.

Sentences may be simple, compound, complex, or compound-complex depending on clause structure. Declarative, interrogative, imperative, and exclamative types serve different speech functions. Spoken sentences are bounded by prosody more than by punctuation.

Defining sentencehood across languages is nontrivial because some languages favor clause chaining without clear equivalents of European sentence boundaries. Nonetheless the sentence remains a practical unit for description, pedagogy, and most writing systems.

• Grammatical unit expressing a complete proposition
• Built from one or more clauses
• Classified by structure and function
• Marked by prosody in speech and punctuation in writing