A sentence is the largest grammatical unit in language that communicates a complete thought. In most cases, a sentence needs to contain a subject and a verb, forming a clause simplex or clause complex. It also must make sense on its own and include a punctuation mark, like a period (.), a question mark (?), or an exclamation mark (!).
To write well, you need to be familiar with the basic principles of sentence structure. Sentences are categorized by their function: declarative, interrogative, imperative, and exclamatory. Sentences can also be grouped by their structure: compound, complex, and dependent.
Understanding how to organize sentences and how to identify common sentence errors will help you improve your writing. Common mistakes are comma splice and fused sentence, sentence fragment, and agreement.
To avoid comma splice and the fused sentence, separate the two main (independent) clauses with a semi-colon or a coordinating conjunction, such as and, but, for, nor, so, yet, and unless. Alternatively, use relative pronouns such as who, what, whenever, or which to form a subordinate clause.
For example, he always works in his yard on Saturdays. He loves the flowers and shrubs that screen his house from the street.