A sentence is a group of words that are joined together to mean something. A sentence is the basic unit of language. It expresses a complete thought. It does this by following the grammatical basic rules of syntax. For example: "Ram is walking".
A complete sentence has at least a subject and a main verb to state (declare) a complete thought. Short example: She walks. A subject is the noun (name) which is doing the main verb. The main verb is the activity that the subject is doing.
In English and many other languages, the first word of a written sentence has a capital letter. At the end of the sentence there is a punctuation mark depending on whether it is a statement, a question, a command, a request or an exclamation.[1]