Article: An absolute phrase, also called a nominative absolute, modifies the entire sentence. While they usually come before the rest of the sentence, they may also come after the main clause. An absolute phrase usually has its own subject and is generally formed with a "noun" and a "participle" (an "-ing" or "-ed" word).  Here is an example of an absolute phrase beginning a sentence: “Her homework completed, Sujata left to meet her friends.” Here is an example of an absolute phrase concluding a sentence: “The couple hurried home, the cold nipping at their faces.” This phrase modifies the entire main clause before it. Adverbial clauses begin with subordinating conjunctions, which connect the clause to the main sentence. Adverbial clauses are always dependent because of these conjunctions, and they cannot stand on their own. They may be placed at the beginning of the sentence or elsewhere.   Common subordinating conjunctions include because, although, whereas, unless and since. For example, here is an adverb clause that begins a sentence: “Because your input at the group meetings is always creative and insightful, I'm putting you in charge of the project.” Here is an adverb clause later in a sentence: “Joe decided not to ride on the roller coaster, even though he enjoyed it, because he had just eaten a huge chili dog.” If you have a series of three or more items, use commas to separate each item.  For example, here is a list separated by commas: “At the store I will buy apples, oranges, pears, and bananas.” Do not place commas before or after the list or series. This comma usage is incorrect, as shown in this example: “At the store I will buy, apples, oranges, pears, and bananas, to make fruit salad tonight.” Do not use commas when all the items in a series are linked by and, or, or nor. For example, here is a list of items linked by and: “Kyle and Spike and Brenda and Willow all went to the concert.” If all of the items in your series are phrases instead of single words, or if the items in your list contain commas, it is acceptable to use semicolons to separate the items instead of commas: “You have a choice of two breakfasts: granola, orange juice, and coffee, which is fairly cheap; or bacon, sausage, and eggs, which is more expensive.” ” The Oxford comma (also known as the Harvard comma) is a comma placed before the final item in a list or series. It is the topic of some debate, with some people advocating against it and others insisting that it always be used. The goal of the Oxford comma is clarity, so use it when the last two items in your series should be clearly separated.  For example, consider this sentence: “I would like to dedicate this book to my parents, my professor and John F. Kennedy.” With this punctuation, it looks as though your parents are your professor and John F. Kennedy. Using the Oxford comma will prevent this confusion: “I would like to dedicate this book to my parents, my professor, and John F. Kennedy.” Using an Oxford comma will never be grammatically incorrect, so if you’re unsure whether you need it, use it anyway. Here's how to know whether the adjectives are functioning independently: If you could insert the word "and" between the adjectives without changing the meaning of the sentence (or producing gibberish), they are functioning independently and a comma should separate them.  For example, here is a sentence with a series of adjectives that is punctuated correctly: People who purposefully misuse grammar are brutish, irresponsible, mean-spirited troglodytes who mangle our beautiful, versatile language.  Some word pairs act as a single word (disc jockey, young man).  Commas are not necessary with these. Do not use a comma if the adjectives are joined by a conjunction! Do not use a comma if the adjectives are of unequal weight; for example, if one of the adjectives is a color or number and the other is a quality, you would not use a comma. For example, "I have a big red wagon" would not take commas, while "I have a rusty, well-loved wagon" would. Each of the elements in a date (weekday, month and day, and year) should be separated by a comma. Also use a comma to separate the elements in an address, or when referring to a city and state or country. For example, you would use a comma in this sentence: “I love to visit Tokyo, Japan.”  Here is an example of correct comma usage for a date: “This WikiHow was written on Monday, May 14th, 2007, in Maryland.” When only the month and year appear, do NOT use a comma: “I wrote this article sometime in May 2007.” Here is an example of correct comma usage for an address: “Her new address is 1234 Main Street, Anytown, Maryland, 12345.” When the elements of the address are joined by a preposition, no commas are needed: “It is on Highway 10 near Pensacola in Florida.” The salutation is the greeting at the beginning of a letter, such as "Dear John." The closing greeting should also be set off with a comma: "Sincerely yours, Hakim." When writing business letters, it is customary to use a colon rather than a comma: "To Whom It May Concern: [body of letter]"

What is a summary?
Use a comma to separate an absolute phrase. Use a comma to separate an adverb clause. Use commas to separate things in a list or series. Understand the “Oxford Comma. Use commas between two or more adjectives of equal weight that independently modify a noun. Use a comma to separate dates and addresses. Use a comma at the salutation and close of a letter.