Well, what kind of clause do you mean? There are four types of clauses : independent (main), dependent (subordinating), relative (adjective), and noun. They all have a subject and a verb and consequently express a complete thought. However, only the independent clause can stand on its own. The other clauses need to be paired up with an independent clause to really make sense.
THE INDEPENDENT CLAUSE Every independent clause will follow this pattern: subject + verb = complete thought. Lazy students whine. Students = subject; whine = verb. My dog loves pizza crusts. Dog = subject; loves = verb.
A dependent (subordinate) clause will follow this pattern: subordinating conjunction or relative pronoun + subject + verb = incomplete thought. Under the dependent clause umbrella, we’ll find adverb (subordinating) clauses, adjective (relative) clauses, adverbial clauses, and noun clauses.
Some subordinating conjunctions that can start a adverb clause: The subordinate conjunction has two jobs. First, it provides a necessary transition between the two ideas in the sentence. This transition will indicate a time, place, or cause and effect relationship. after although as because before even if even though if in order that once provided that rather than since so that than that though unless until when whenever where whereas wherever whether while why
An adjective (relative) clause will begin with a relative pronoun [such as who, whom, whose, which, or that] or a relative adverb [when, where, or why]. The patterns look like these: relative pronoun or adverb + subject + verb = incomplete thought. relative pronoun as subject + verb = incomplete thought. Let’s look at some examples of adjective clauses!
Whom Mrs. Russell hit in the head with a chalk eraser Whom = relative pronoun; Mrs. Russell = subject; hit = verb. The boy whom Mrs. Russell hit in the head with a chalk eraser has finally stopped talking in class. Where he chews and drools with great enthusiasm Where = relative adverb; he = subject; chews, drools = verbs. The dog likes to lie under the table, where he chews and drools with great enthusiasm. That had spilled over the glass and splashed onto the counter That = relative pronoun (as subj.); had spilled, splashed = verbs. The red punch that had spilled over the glass and splashed onto the counter was quickly wiped up before it could stain the formica. Who loves pizza crusts Who = relative pronoun (as subj.); loves = verb. When we go to Pizza Hut, we save our leftovers for Andy, who loves pizza crusts.
Any clause that functions as a noun becomes a noun clause. Look at this example: You really do not want to know the ingredients in Aunt Nancy's stew. Ingredients = noun. If we replace the noun ingredients with a clause, we have a noun clause: You really do not want to know what Aunt Nancy adds to her stew. What Aunt Nancy adds to her stew = noun clause.
Now that you are experts on clauses, we are going to talk about punctuating them.
Today we’ll focus on punctuating relative (adjective) clauses, clauses that describe a noun. An adjective clause (adjectival clause) is a dependent clause that functions as an adjective, modifying nouns and pronouns. It starts with either a relative adverb: where, when, and why, or a relative pronoun: that, who, whom, whose, or which.
RESTRICTIVE (ESSENTIAL) VS. NONRESTRICTIVE (NONESSENTIAL) CLAUSES 1. Restrictive relative clauses are not set off by commas, while nonrestrictive relative clauses are. 2. As a general rule, the pronoun "that" should be used for restrictive relative clauses, and "which" should be used for nonrestrictive relative clauses. SO WHAT’S THE DIFFERENCE BETWEEN A RESTRICTIVE AND NONRESTRICTIVE CLAUSE?
NONRESTRICTIVE RELATIVE CLAUSES If a relative clause adds parenthetical, nondefining information, it is nonrestrictive (nonessential). A nonrestrictive (parenthetical) element is set off by commas, as in these examples. Mr. Smith, who is a well-respected lawyer, has just retired from active practice. Professor James, who is an expert in Victorian poetry, will be giving a lecture tonight.
Mr. Smith, who is a well-respected lawyer, has just retired from active practice. Professor James, who is an expert in Victorian poetry, will be giving a lecture tonight. You can take away the clause (in red) and you still know EXACTLY who the writer is talking about. The subject is clearly identified by, in this case, his name. The clause simply provides extra information, parenthetical information. You can remove the clause and it’s perfectly who just retired from active practice and who will be giving a lecture tonight. The clause is nonessential so it is nonrestrictive. Since it’s not essential to your understanding, you need to surround it with commas.
If the noun being described by your clause is already clearly defined, then your clause is providing parenthetical or extra information. PARENTHETICAL INFORMATION= NONESSENTIAL INFORMATION= NONRESTRICTIVE CLAUSE= COMMAS SURROUNDING THE CLAUSE REQUIRED REMEMBER
What?!?!? Restricted Claus? Just what is Santa watching on that computer of his?
When the relative clause limits or restricts or identifies the noun or pronoun it modifies, it is restrictive, and it is not set off by commas. Look at the difference between these two sentences. My sister who has three children is named Jane. (restrictive) My youngest sister, who has three children, is named Jane. (nonrestrictive) Apparently, the writer has more than one sister. In the first sentence, the clause identifies which sister she’s talking about, the one with three children. The clause is essential or restrictive, so no commas are needed. In the second sentence, the same clause has become nonessential or nonrestrictive. Why? Because we already know which sister the writer is talking about, her YOUNGEST sister. The clause now holds extra information and needs commas surrounding it. If you remove the clause from the first sentence you may think the writer only has one sister. You change the meaning and your understanding. If you remove the clause from the second sentence, you still understand what the author is trying to say.
If the relative clause IDENTIFIES or RESTRICTS or LIMITS the noun it’s describing, then your clause is providing information ESSENTIAL to the reader’s understanding. ESSENTIAL INFORMATION= RESTRICTIVE CLAUSE= NO COMMAS