Punctuation
Middle SchoolPunctuation is the silent grammar of the page — a set of marks that groups words, signals pauses, and encodes relationships the voice would carry in speech. Used well, it is invisible; used badly, it derails meaning.
its — possessive
- Shows belonging, like his and hers.
- Never takes an apostrophe.
- “The dog wagged its tail.”
- Test: it names something owned.
it's — contraction
- Always means “it is” or “it has.”
- The apostrophe marks the missing letter.
- “It's raining” = “It is raining.”
- Test: can you expand it to “it is”?
The marks and their jobs
| Mark | Primary function |
|---|---|
| Period (.) | Ends a declarative sentence; marks a full stop. |
| Comma (,) | Separates items in a list, sets off clauses and non-essential elements, follows introductory phrases. |
| Semicolon (;) | Joins two closely related independent clauses; separates complex list items. |
| Colon (:) | Introduces a list, explanation, or quotation; the part after it delivers what the part before promised. |
| Dash (— ) | Marks an abrupt break, an interruption, or an emphatic aside. |
| Apostrophe (') | Shows possession (the dog's bone) and marks omission in contractions (can't). |
| Quotation marks (" ") | Enclose direct speech and titles of short works. |
| Question / Exclamation (? !) | Mark interrogative and exclamatory sentences. |
| Parentheses / Brackets | Enclose supplementary or editorial material. |
Three high-value rules
- The serial (Oxford) comma: the comma before the final and in a list — "bread, butter, and jam." It prevents ambiguity ("I thank my parents, Ayn Rand and God" reads very differently with the comma).
- Restrictive vs. non-restrictive: information essential to identifying the noun takes no commas ("The runner who fell withdrew"); non-essential information is fenced with commas ("Ravi, who fell, withdrew").
- Its vs. it's: its is possessive (no apostrophe, like his); it's is only ever "it is" or "it has."
The deepest way to understand punctuation is hierarchy of separation. Marks form a scale of increasing division: the comma is the lightest pause, the semicolon a stronger one, the colon a pointing-forward, and the period a full stop. Choosing a mark is choosing how hard to separate two ideas — and therefore how closely you want the reader to feel they belong together.
The colon and semicolon are the most misunderstood. A colon is a promise: what follows fulfils what preceded ("She had one goal: to win"). A semicolon is a hinge between two complete, related thoughts ("The theory was elegant; the data disagreed"). Test the semicolon by replacing it with a period — if both halves stand as full sentences, the semicolon is correct.
All three can set off an interruption, but they differ in volume. Commas whisper the aside ("My brother, a doctor, agreed"). Parentheses lower it further, almost to a footnote ("My brother (a doctor) agreed"). Dashes shout it — they add drama and emphasis ("My brother — a doctor, no less — agreed"). Match the mark to the loudness you intend.
Exercise: repunctuate a passage
Below is an under-punctuated paragraph. Read the corrected version and the reasoning for each change.
its a long journey the travellers were exhausted however they pressed on they had three things left water a map and hope.
After (corrected)It's a long journey; the travellers were exhausted. However, they pressed on. They had three things left: water, a map, and hope.
Change by change:
- its → It's — needs the contraction "it is," and a capital to start the sentence.
- journey; the travellers — a semicolon joins two related independent clauses more tightly than a period would.
- exhausted. — full stop closes the thought before a new sentence.
- However, — a conjunctive adverb opening a sentence takes a following comma.
- left: — a colon introduces the list that fulfils "three things."
- water, a map, and hope — serial comma before and for clarity and rhythm.
Now you try: punctuate — "the verdict was clear the jury had decided the evidence was overwhelming." (One good answer: "The verdict was clear: the jury had decided. The evidence was overwhelming.")
When should I use a semicolon instead of a comma?
AUse a semicolon to join two independent clauses that are closely related but not linked by a coordinating conjunction: "The lecture ran late; nobody left." A comma there would be a splice. Also use semicolons to separate list items that themselves contain commas: "The tour visited Paris, France; Rome, Italy; and Bern, Switzerland." Everywhere else, a comma is the lighter and usually correct choice.
Where does the apostrophe go for plural possessives?
AFor a plural noun that already ends in -s, add only an apostrophe: "the students' results" (belonging to many students). For a plural not ending in -s, add 's: "the children's books." For a singular noun, always add 's, even if it ends in s: "the boss's office," "James's car." Remember that possessive pronouns (its, hers, ours, theirs, yours) never take an apostrophe.
Do commas and periods go inside or outside quotation marks?
AIt depends on the convention. In American style, commas and periods always go inside the closing quotation mark: She said "yes," and left. In British style, they go inside only if they belong to the quoted material and outside otherwise: She said "yes", and left. Colons and semicolons go outside in both systems. Choose one convention and apply it consistently throughout a document.
Is the Oxford comma required?
AIt is a style choice, not a grammatical law — but it is the safer default because it prevents ambiguity. Without it, "We invited the strippers, JFK and Stalin" can be read as naming the two strippers. With it — "the strippers, JFK, and Stalin" — three separate parties are clearly meant. Some house styles (notably journalism) drop it to save space; academic and book publishing generally keep it. Whichever you pick, be consistent.