So with this in mind – and without having to take an entire course of eighth-grade English over or laboriously flip through Strunk and White to find the details of every grammar or punctuation rule – let’s examine the top six most common grammar and punctuation mistakes in layman’s terms. 

Who and whom should be used when speaking of human beings or named animals, whereas that and which should reference inanimate objects or animals without a name.  In particular, who is used when a word is the subject of a sentence, phrase or clause – such as, “The man who sold the house already left.” Conversely, whom should be used when it modifies a word that is the object of a preposition or verb, such as, “The girl to whom he referred was Sheila.” 

Speaking of that and which, which often get confusingly switched with who and whom, these two words might be the ones I see used improperly most often.  That and which fall under rules for essential and nonessential clauses.  Put simply, “which” is the only pronoun that should ever be used to start a nonessential clause, which is a clause that can be removed from the sentence and not change the sentence’s meaning or completeness.  For instance, the end of that last sentence could be deleted after the comma and still allow for the words left before the comma to make sense as a complete sentence.  “Which” is also the one of this pair that always has a comma before it when it leads a nonessential clause.  An essential clause, on the other hand, should never have a comma before it, because after all, it is essential to the meaning of the sentence.  An example of such an essential clause that starts with “that” would be, “The car that changed lanes illegally was pulled over by the police car.” The essential clause here that begins with “that” would, if it were removed from the sentence, take away from the full, intended meaning of the sentence.   

The word “over” should only be used to describe a physical situation, such as, “The bridge led over the pond.” It is often misused in research papers in sentences like, “There were over 50 males who participated in the study.” In this case, “more than” is always the better choice – for example, “More than 40 percent of the participants were male.” One exception is, on occasion, that over can be used with numerals – for instance, “He is over 50.” As the Associated Press Style Guide instructs in such cases, “Let your ear be your guide.”

The science of using commas in lists of three or more things is an unperfect one.  In most writing styles, a comma should not be used after the second item and the word “and” or “or” – such as “apples, oranges and bananas,” or “pigs, horses or cows.” However, there is always an exception to the rule, and commas have several exceptions.  For one thing, MLA and APA Format, which are the most common styles used for scholarly dissertations, directly contradicts this basis rule by requiring that commas do appear between a second item in a list and the “and” or “or.” 

However, even this basic rule has an exception in typical English language style when the words in a list are verbs.  In the case of a list of three or more verbs, a commas is always used after the second verb and the “and” or “or.” A good example would be, “She biked, jogged, and played racquetball at the gym today.”

Quotation marks are no problem to some and an enigma to others.  The basics to know are that in proper American English, quotation marks are double, “like so,” and should always frame the entire quotation, including the punctuation.  For instance, “I don’t know what I did before I found PapersEditing,” the happy client said.  British English, however, throws some for a loop because of that language’s practice of using single quotation marks, ‘like so.’ Likewise, MLA and APA styles makes things even more complicated by leaving punctuation outside of the quotation marks for incomplete thoughts or sentences.  For instance, he said he’d “never use another essay proofreading after he found her”.  Again, though, this is the exception to the rule.  When in doubt, however, go with the basics – double quotation marks with punctuation inside.   

The use of an ellipsis ( ...  ) is, to some, a mystery, and to others commonplace.  If you fall into the second of those groups, chances are you’re using an ellipsis way too much in your writing.  In fact, there is really rarely a reason for this punctuation to be used, except when you need to show the deletion of one or more words when condensing quotations, documents or texts.  Essentially, the ellipsis denotes a portion of text left out, and should always have a space before and after it.  It can alternately be used to signify a pause or hesitation in speech or a thought the speaker or writer leaves incomplete, but most of such uses would be better substituted with a dash before choosing to use an ellipsis (and this is especially true if an ellipsis has been used in the same writing for its first purpose – to denote a portion of text that’s been condensed).  When in doubt about how to denote a pause, I always recommend a dash before using an ellipsis.  For a thought that trails off incompletely, I do allow for an ellipsis if it has not been used for a true omission of words in other parts of the same writing. 

In sum, these are just the top six most common grammar and punctuation mistakes I see in my daily editing work.  There’s always more that come up, depending on the writer and what sticks and doesn’t for each of us from that eighth-grade English class years ago.  And for the rest – well, that’s what editors at PapersEditing are for!