Common word usage and punctuation mistakes
Common grammar errors
Everyday/ Every day
This is one of the most common mistakes I see. Almost every day I see semi-trucks announcing that if you work for their company, you will be home "everyday." Seeing this mistake almost daily drives me crazy. "Everyday" is an adjective. Dictionary.com defines it this way: "1. of or pertaining to every day; daily: an everyday occurrence. 2. of or for ordinary days, as contrasted with Sundays, holidays, or special occasions: everyday clothes." Generally, if when you substitute another adjective for "everyday" in your sentence and your sentence no longer makes sense, you have used it incorrectly and you mean "every day." Using the two examples above from Dictionary.com, another adjective could be substituted: "an exciting occurrence" or "purple clothes."
"Every day" is a noun phrase, where "every" modifies "day." "Every" in "every day" is an adjective but "day" is a noun." Those ads on the semi-trucks I mentioned earlier mean "every day," not "everyday." "Every day" is most commonly used to describe how often you do something: "Every day I take a shower," or "I eat food every day." Dictionary.com says "everyday" is synonymous with "daily" but I think more often "daily" can be substituted for "every day": "Daily I take a shower," or "I eat food daily." If you do not actually conduct a certain activity every single day, then do not use "daily" or "every day." Seeing if you can insert the word "single" between "every" and "day" is a great way of verifying if you are using the correct form. Saying "I go to the store every single day" makes sense and flows, but saying "Breathing is an every single day occurrence," sound awkward and choppy. The correct way to say that sentence would be "Breathing is an everyday occurrence."
That vs. Who
Most people I know make this mistake, because they don't know they are making it. If you are talking about a person, use "who" not "that." Example: I know this girl who eats peanut butter and cream cheese sandwiches. Dictionary.com defines "who" as "(used relatively in restrictive and nonrestrictive clauses to represent a specified antecedent, the antecedent being a person or sometimes an animal or personified thing): Any kid who wants to can learn to swim." As you can see from the example sentence, the person being discussed doesn't have to be a specific individual in order for "who" to be used. If you are talking about a human, always use "who" not "that." So saying "I know a girl that eats peanut butter and cream cheese sandwiches" is not correct.
"Was" is used for the simple past tense to describe what a single individual did: "I was walking to Steve's house yesterday afternoon." "Sarah was running when she tripped and fell." I do not know anyone who (notice it's who not that) says "were" in place of "was" in sentences like these. However, I do know many people who incorrectly use "was" in the subjunctive mood. Loosely defined, the subjunctive mood is used for hypothetical situations and wishes. If you ever start a sentence with "I wish" you will always want to use "were" not "was": I wish it were possible to fly. It would be incorrect to say "I wish it was possible to fly." It sounds grammatically correct, but it's not. Take hypothetical situations: "If I were (not "was") able to teleport, I would go to Italy right now." If what you are talking about didn't actually take place yet, and you are describing a wish or a hypothetical situation, use "were."
Good vs well
Quite often, many people I know use "good" when they mean "well," mainly when they say something will or does "work good." I cringe slightly every time I hear someone say those two words together. When I was younger, someone more knowledgeable than myself once advised me to think about it this way: You feel good but you do things well. You can say you are good at performing a task, just never say you do it "good." "Mary danced the waltz quite well last night," is correct. To many, it's not obvious that saying "Mary danced the waltz quite good last night," simply sounds substandard. To me, using "good" when you mean "well" sounds just as clunky and uneducated as saying "ain't" or "gonna", or using double negatives. Using the "feel good, do things well" rule works well for me. Just remember you cannot perform tasks "good." "Good" is an adjective and adjectives don't modify verbs. Adverbs modify verbs. To say you do something "good" as in "I can juggle good," doesn't work because you have just tried to modify a verb with an adjective. Adjectives modify nouns, not verbs.
I feel embarrassed for anyone who doesn't have the rules of the apostrophe figured out yet. It's sad that our education system has failed so many students that they grow up to be adults who run around making the same ridiculous mistakes over and over again. Here are the rules: 1. As a singular possessive (one person or thing owns something else) put the apostrophe before the S: "Sarah's eyes" or "The truck's tires." The eyes belong to Sarah and the tires belong to the truck. The exception to this rule is if the thing or person who owns the object has a name that ends in an "S" sound, you can choose to leave off the "S" after the apostrophe: "The asparagus' flavor was rich." In this case, the asparagus owns the flavor, but it would be awkward to pronounce two "S" sounds so you just pronounce it as though the second "S" were not there. 2. As a plural possessive (more than one thing or person owns something else) the apostrophe comes after the S: "The trucks' tires" or "The cats' food." More than one truck's tires, and many cats own the food. 3. When talking about a letter or number: "The l's in the word 'parallel' are in fact parallel to one another." The apostrophe here is used to let the reader know to pronounce the whole letter, and not to sound out the letter, to say "El's" and not pronounce the L as you would in the sound "la." I also want to cover "its" versus "it's." "It's" is a contraction of the words "it" and "is": "It's a lovely day out today." "It's" can also be a contraction of the words "it" and "has": "It's been a great day." "Its" (no apostrophe) is the possessive form of the pronoun: "The truck is awesome. Its (meaning the truck's) metallic paint really shows off the curves of the (or "its") hood."
I hope these rules are familiar to 99.9 percent of you if not all of you. I just had to include this one because I grow SO tired of seeing an apostrophe put in when people are writing simple plurals as in "I have many car's I can sell you." That so many people continue to make such a horrendous mistake leads me to believe elementary school teachers need to overhaul their grammar lessons and force kids to read a whole lot more, so they see the correct punctuation in print.
As with all my writing, if you read something here that seems off or you know is just wrong, I encourage you to correct me. The above matters bother me because I am very familiar with these grammar issues. There are a few grammar and punctuation issues I am not so familiar with, so if I have butchered them here, please let me know so I can correct them and not seem like such a hypocrite.