A clause is a group of words that contains a subject and a verb. It can express a complete thought, making it an independent clause, or it can be part of a larger sentence, known as a dependent clause. For example, in the sentence "She runs every morning," "She runs" is an independent clause. Clauses are essential in constructing sentences and can be combined to add complexity. A sentence can have multiple clauses, such as in "Although it was raining, we went for a walk." Here, "Although it was raining" is a dependent clause, while "we went for a walk" is an independent clause.