You can have a wide vocabulary and solid grammar and still send an email that reads as careless — and the culprit is almost always punctuation. A comma in the wrong place, an apostrophe that wanders, a sentence that runs on for four lines without a full stop: these are the small marks that quietly decide whether your writing looks professional or rushed. The good news is that English punctuation is far more logical than it feels. You don't need to memorise a rulebook. You need to understand what each mark is actually for, and a handful of patterns will carry you through almost everything you write.
The Comma Does More Than You Think
Most punctuation worries come down to the comma, because it does several jobs at once. It separates items in a list ("we offer reading, writing, and speaking classes"). It marks a pause after an introductory phrase ("After the lesson, we'll review your notes"). And it fences off extra information that you could remove without breaking the sentence ("My teacher, who is from London, corrects my pronunciation").
The classic trap is the comma splice — joining two full sentences with only a comma. "I studied hard, I passed the exam" is wrong. You have three easy fixes: use a full stop ("I studied hard. I passed the exam"), add a joining word ("I studied hard, so I passed the exam"), or use a semicolon. When in doubt, ask whether what sits on each side of the comma could stand alone as a sentence. If both can, a lone comma isn't strong enough to hold them together.
Apostrophes: Two Jobs, One Mark
The apostrophe causes more public embarrassment than any other mark in English, yet it only does two things. It shows possession ("the student's book," "the students' books") and it marks missing letters in a contraction ("do not" becomes "don't"). That's the whole job.
The pair that catches everyone is its and it's. Here's the rule that never fails: it's always means "it is" or "it has." If you can't replace it with those words, you want its, with no apostrophe. "The school updated its website" — no apostrophe, because nothing is missing. "It's a great course" — apostrophe, because it means "it is." Plurals never take an apostrophe either: you have three exams, not three exam's.
Full Stops Beat Long Sentences
If you only fix one thing in your writing, make it this: use more full stops. Learners often try to sound advanced by stringing clauses together with "and," "but," and "because" until a single sentence runs for five lines. It doesn't sound sophisticated — it sounds breathless, and readers lose the thread halfway through.
Short sentences are a gift to the reader. They're easier to punctuate correctly, easier to follow, and they make your meaning land. When you finish a draft, read it aloud. Every time you naturally pause for breath, you probably need a full stop or at least a comma. If you reach the end of a line and still haven't taken a breath, break it up.
The Marks That Change Your Tone
A few marks do quiet work on how you come across. A colon introduces something — a list, an explanation, an example ("You'll need three things: a notebook, a pen, and patience"). A semicolon links two related sentences more gently than a full stop ("The grammar was fine; the punctuation let it down"). A dash adds a sharp aside or an afterthought — like this one — and feels more informal than brackets.
Question marks and exclamation marks deserve a word of caution. One exclamation mark can sound friendly; three in a row ("Thanks!!!") can read as unprofessional in a work email. And a question mark belongs only on an actual question, not on a polite request — "Could you send me the file." is a softened instruction, while "Could you send me the file?" genuinely asks. Small choices, but they shape how the reader hears your voice.
None of this needs to be memorised overnight. Punctuation gets easier the moment you start reading your own sentences aloud and noticing where the pauses fall. If you'd like a teacher to look at your real writing — your emails, essays, or reports — and show you the patterns that keep tripping you up, that's exactly what we do in our online courses at Kensington English: clear feedback on the writing you actually do, so the rules stop feeling like a test and start feeling like second nature.
