Common Errors

You've done the work. There's a draft in front of you — a school essay, a covering letter, the report that simply has to land — and then it arrives. The red pen. The green squiggle. Or that quiet, cold little feeling that a sentence is "off" and you can't quite say why.

S–V AGREEMENT. FRAGMENT. ITS/IT'S. COMMA SPLICE. AWKWARD.

Here's the thing. That mark is almost never proof that you "can't do grammar." It's a symptom — a small flag pointing at one particular joint in the machine. Something in the sentence has slipped, and the mark is just the alarm going off. Name the joint, and you can fix it.

Welcome to the clinic.

The deal — read this first

This pillar isn't like the rest of the library, so it's worth a moment to explain how it works.

Pillars 1–9 are where the rules live. The full explanations, the "why," the practice, the long, patient view. If you want to understand apostrophes or the verb system properly, that's where you go.

Pillar 10 is the walk-in clinic. You arrive with a squiggle, a comment, or a hunch — and every article in here does the same four things, fast:

1. Names the symptom in plain English — the red-pen line, the checker message, the gut feeling — not jargon for its own sake.
2. Diagnoses it with a memorable test you can run yourself next time, without a textbook open.
3. Fixes it with two or three clear wrong-versus-right moves.
4. Sends you home — a prominent link back to the pillar that owns the real rule, for when you want the whole story rather than the patch.

That's it. We are not going to re-teach English from the ground up every time something gets marked. Nobody's born knowing this, and you don't need to relearn it from scratch either. You just need the right door.

Before you go further, here's the map. This page will help you: - Treat every "grammar error" as a symptom, not a personal failing. - Find the right cluster — word, sentence, tense, pronoun, confusable, punctuation, or register. - Reach for the Top-20 Checklist when you want a quick once-over. - Step into one of the three sub-hubs, or straight into a single clinic article. - Link home to Pillars 1–9 whenever you want the full rule, not just the fix.

Start here if you only have a feeling: the Top-20 Checklist

Let's be honest — scrolling a long list of error names while your deadline glows at you is nobody's idea of a good evening. So when the whole page feels suspect and you can't name what's wrong, don't re-read the entire library. Run the short list.

The Top-20 Grammar Errors Checklist gathers the handful of problems — and pseudo-problems — that produce most of the red pen, most of the squiggles, and most of the late-night fretting, on school work and working life alike. It's built for a final pass: scan, spot, fix, move on. Use it after a draft rather than instead of one, lean hardest on your own soft spots (if their and there already haunt you, look there first), and follow it into the individual clinic articles whenever something won't quite settle.

→ [Top-20 Grammar Errors Checklist]

Not sure which door? The three sub-hubs

Think of these as the three corridors off reception. If you know roughly what's bothering you, pick a corridor and it'll route you to the right clinic article.

[Word-level clinic] — when the mark is on one word (or two that look alike), not on the shape of the whole sentence. Pronoun forms, articles, prepositions, quantifiers, negation, and the confusables that fill every red-pen story.

[Sentence-level clinic] — when the problem is "this doesn't feel like one proper sentence" or "I get lost halfway through." Fragments, run-ons, comma splices, dangling modifiers, wonky parallel lists, tense and agreement wobbles.

[Punctuation, style & myths clinic] — when it's the marks between the words, or when the "error" may not be an error at all. Commas, apostrophes, semicolons and colons — plus the register calls and debunked rules that get writers scolded for things that were never really wrong.

The full cluster map — pick your symptom

Not every mark sits neatly in one corridor, so here's the finer map. Each cluster below is a door; each opens from the feeling, not the textbook definition, and each sends you home to the pillar that owns the underlying rule.

Tense & agreement — "The list of options are…," or a story that starts in one time and drifts into another. The verb quietly agreeing with the nearest noun instead of the real subject, or a timeline that won't hold still. → [Tense & agreement clinic] · full rule: Pillar 4 (the verb system) and Pillar 5 (agreement and antecedents).

Sentence structure — "FRAGMENT." "RUN-ON." "This sentence is trying to do three jobs at once." Clauses joined with nothing, or with just a comma, or chopped off before they're finished; modifiers left dangling; lists that lurch from noun to verb to whole clause. → [Sentence structure clinic] · full rule: Pillar 3 (sentences, clauses, modifiers, parallel structure).

Pronouns — "Between you and I…," "who or whom?," a "they" that doesn't clearly point at anyone. Wrong case, wrong form, or a pronoun that's floated too far from the noun it stands for. → [Pronouns clinic] · full rule: Pillar 2 (pronoun forms and case) and Pillar 5 (antecedents).

Word-level grammar — a circled a/an/the, a preposition, a double negative. The small function words teachers and checkers love to ring in red. → [Word-level grammar clinic] · full rule: Pillar 2 (parts of speech, articles, prepositions, quantifiers, negation).

Confusables & lookalikes — its/it's, your/you're, their/there/they're, affect/effect, loose/lose, then/than. Two words that sound the same or look alike, and the wrong one turned up. → [Confusables clinic] · full rule: mostly Pillar 8 (spelling and confusables) — but its/it's and whose/who's live in Pillar 2, because those are about apostrophes and pronoun forms, not spelling.

Logic, negation & punctuation — a double negative, a misfiring comma, an apostrophe in the wrong place. The marks that quietly change your meaning: a comma that splices, an apostrophe that pluralises by mistake, a "not… no" that cancels itself out. → [Logic, negation & punctuation clinic] · full rule: Pillar 6 (punctuation mechanics), with negation in Pillar 2.

Register & myths — "too informal," "passive voice," "don't start with And," "never split an infinitive." Often not errors of English at all, but questions of audience — or rules that never really held. → [Register & myths clinic] · full rule: Pillar 9 (register and style).

Pro-Tip: When a checker flags something, read the sentence first, not the label. "Possible agreement error" is a hint, not a verdict. Run the clinic test, keep the fix that matches what you actually meant, and ignore the rest.

What "wrong" sometimes isn't

A warm word before you pick a door.

Not every mark is an error of English. Sometimes it's dialect — a pattern that's perfectly consistent in one variety of English and "wrong" only against a school standard. Sometimes it's register — fine in a text to a friend, odd in a formal report, and the other way round too. Sometimes it's house style — organise [US: organize], colour [US: color], the serial comma, the date format — a choice, not a moral failing. And sometimes it's simply a myth: a rule that never quite held, kept alive by one strict teacher and passed down like folklore.

The clinic will tell you which is which. Where a supposed error is really taste, audience, or history, we'll say so plainly — because "correctness" should never be a stick to make anyone feel small about how they already speak. You get to decide what your piece needs.

Common Mistake: Treating every green squiggle as gospel. Grammar software is pattern-matching; it doesn't know your reader, your house style, or your joke. Use it as a second pair of eyes — then decide for yourself.

Where to go from here

You've already done the hard part — caring that the writing lands. The red pen, the squiggle, the odd cold feeling: those are just reception tickets. Pick the door that matches the mark, run a quick test, patch what's broken, and open the big textbook only when you want the why.

The good news is that once a symptom has a name and a test, it usually quietens right down. And for the rest — the myths, the taste calls, the "is this even wrong?" moments — you've got a clinic that will tell you the truth rather than add to the fog.

Right. Which door matches the mark on your page?