07 — Punctuation & capitalization basics

What this fixes for you: the lowercase “i”, the missing full stops, and the run-on sentences that make your commits and Slack messages read as rushed. Small marks, big difference in how senior your writing looks.

The rule in 30 seconds

• Start every sentence with a capital letter, and always write I (the word for yourself) as a capital — never i.
• End every sentence with a closing mark: . for a statement, ? for a question, ! for strong emphasis (use ! rarely at work).
• Capitalize proper nouns — names of people, products, and tools: GitHub, Slack, PostgreSQL, Docker, Laravel.
• Use commas to break up lists and clauses so a long sentence has air; use backticks around code so prod doesn’t read as a typo.

Why this trips you up

You type the way you text — lowercase i, no full stops, and one long line where several sentences chain together with no breaks (your own message: “i already know but as of now i am making so much mistake”). In code that’s fine, but in a PR or standup it makes a reader work to find where one thought ends and the next begins. The fix is mechanical, not creative: capital at the start, mark at the end, comma in the middle.

See it / fix it

❌ What you tend to write	✅ Correct	Why
can u do reaseach on grammer for me	Can you do research on grammar for me?	Capital start, real words not u/reaseach/grammer, and a ? because it’s a question.
i already know but as of now i am making so much mistake	I already know it, but right now I'm making so many mistakes.	Capital I (twice), full stop, comma before but, and many mistakes (countable → plural).
fixed the bug it was a null pointer	Fixed the bug. It was a null pointer.	Two thoughts = two sentences. A full stop, then a new capital.
i deployed to prod but it failed i rolled back	I deployed to prod, but it failed, so I rolled back.	Capital I, commas to separate the chained clauses, no run-on.
can you review my pr when ur free	Can you review my PR when you're free?	PR is capitalized, ur → you're, and it ends with ?.
the api returns 500 check the logs	The API returns 500 — check the logs.	Capitalize the sentence and the proper-ish term API; split the two ideas.
we use postgresql and github actions	We use PostgreSQL and GitHub Actions.	Product names keep their official capitalization.
to open pull request run gh pr create	To open a pull request, run \gh pr create`.`	Add the article a, a comma after the intro clause, and backticks around the command.
done with task lgtm	Done with the task. LGTM!	Add the, end the statement, and LGTM (an acronym) stays uppercase.
i think we need three thing migration seeder and test	I think we need three things: a migration, a seeder, and a test.	Capital I, plural things, a colon to introduce the list, commas between items.

Patterns to remember

Capitalize when:

• It’s the first word of a sentence.
• It’s the word I (always, even mid-sentence).
• It’s a proper noun: GitHub, Slack, PostgreSQL, Redis, Nuxt, Stripe, Monday, June.

Tool names are not yours to lowercase. It’s GitHub, not github; PostgreSQL, not postgresql. When in doubt, copy the spelling from the project’s own homepage.

End marks — pick one per sentence:

Sentence type	Mark	Example
Statement	.	The build passed.
Question	?	Did the build pass?
Strong call-out (rare at work)	!	Don't merge yet!

Comma — the four uses you actually need:

Use	Pattern	Example
Lists	a, b, and c	Add a test, a migration, and a seeder.
After an intro clause	When X, do Y.	After the deploy, watch the logs.
Before but/and/so joining two full sentences	S1, but S2.	It built, but the tests failed.
Around an aside	X, which is Y, …	The cache, which is Redis, was stale.

Test for the “joining” comma: if both sides could stand alone as their own sentence, put a comma before but/and/so. It built ✅ + the tests failed ✅ → It built, but the tests failed.

Colon vs semicolon:

• Colon : introduces a list or an explanation. We need three things: a migration, a seeder, and a test.
• Semicolon ; joins two closely related full sentences without and/but. The deploy finished; the alerts cleared. (When unsure, just use a full stop — it’s never wrong.)

Quotes and code:

• Wrap commands, file names, branches, and values in backticks: run \npm run build`, the `main` branch, set `status` to `paid“.
• Use “quotes” for actual spoken/written phrases or UI labels: Click "Save changes".

In your daily writing

• Commit messages: capital first word, no full stop on the short summary line (git convention), backticks in the body. Fix null pointer in OrderService then a blank line, then The \customer` relation was null after a soft delete.`
• PR titles & descriptions: title is capitalized; the description is full sentences with end marks. End any direct question to reviewers with ? — Should I split this into two PRs?
• Slack standups: still capitalize I and start sentences with a capital. Yesterday I shipped the cache fix. Today I'm on the migration. No blockers. reads far better than yesterday i shipped... today i....
• Code comments: capitalize the first word and end with a full stop. // Guard against a null tenant after deletion. — a comment is a sentence, treat it like one.

Drills

Fix, fill, or choose. Answers are at the bottom — try first, then check.

1. Fix: i pushed the branch can u check it
2. Fix: we use postgresql in dev and sqlite in test
3. Fix: the deploy failed i checked the logs it was a config issue
4. Choose A or B: It built ( A: , but / B: but ) the tests failed.
5. Fill the blank with : or ; — We need three things___ a test, a migration, and a seeder.
6. Fix: can you open pull request for this
7. Fix: i think we have so much bug in this release
8. Choose A or B: After the deploy ( A: watch / B: , watch ) the error rate.
9. Fix: done lgtm ship it
10. Fix: the api returns 500 when ur token is expired
11. Fill the blank with the right end mark — Did the migration run on staging___
12. Fix: i did reaseach on grammer like u asked

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Answer key

1. I pushed the branch. Can you check it? — Capital I, split into two sentences, u → you, and the second is a question (?).
2. We use PostgreSQL in dev and SQLite in test. — Capitalize the sentence and the product names (PostgreSQL, SQLite); add the full stop.
3. The deploy failed. I checked the logs — it was a config issue. — Three thoughts; don’t chain them. Capital start, capital I, end mark. (A dash or full stop both work for the last break.)
4. A — It built, but the tests failed. — Both sides are full sentences, so a comma goes before but.
5. : — We need three things: a test, a migration, and a seeder. — A colon introduces a list.
6. Can you open a pull request for this? — Add the article a, and end with a ? because it’s a request/question.
7. I think we have so many bugs in this release. — bug is countable, so many bugs (plural), not much bug; capital I.
8. B — After the deploy, watch the error rate. — A comma follows an introductory clause.
9. Done. LGTM — ship it! — Separate the statements; LGTM stays uppercase. (Ship it! may take a ! since it’s a strong go-ahead.)
10. The API returns 500 when your token is expired. — Capitalize The and API; ur → your; add the full stop.
11. ? — Did the migration run on staging? — A direct question always ends with a question mark.
12. I did research on grammar like you asked. — Capital I, fix the spelling reaseach → research and grammer → grammar, and u → you.

Part of the Developer English course — see 00-index.md.