In English grammar, a clause is a group of words that contains a subject and a predicate. Clauses can be classified into two main types: independent (main) clauses and dependent (subordinate) clauses.
Independent Clauses: These clauses can stand alone as a complete sentence. They express a complete thought.
Example: "She loves to read."
Dependent Clauses: These clauses cannot stand alone as a complete sentence. They depend on an independent clause to make sense.
Example: "Because she loves to read" (This needs an independent clause to complete the thought, such as "Because she loves to read, she visits the library often.").
While the basic structure and function of clauses are the same in both American and British English, there are subtle differences in usage. American English uses "that" for defining and "which" for non-defining clauses, while British English is more flexible, often using "which" for both. For adverb clauses, American English uses "while" for both "at the same time" and "although," whereas British English often uses "whilst." American English places a comma before "which" in non-defining clauses, a practice also seen in British English but with more flexibility. These differences mainly reflect slight stylistic variations.