What are Period / Full Stop?
A period marks the end of a complete declarative sentence (a statement), a mild imperative (a polite instruction), or an indirect question. It signals to the reader: this unit of thought is complete. Every sentence that does not end with a question mark or exclamation point ends with a period.
Periods are also used in abbreviations, though conventions differ significantly between British and American English. British English tends to omit the period in abbreviations where the last letter of the full word is also the last letter of the abbreviation (Dr, Mr, St). American English usually retains the period (Dr., Mr., St.).
A period and a question mark or exclamation point are never combined at the end of the same sentence. If a sentence ends with a quoted sentence that itself ends in a period, only one period appears.
When to Use a Period
Apply the rules in order: if the sentence is a direct question, use a question mark. If it is an exclamation, use an exclamation point. Otherwise, use a period.
Declarative sentence or imperative + period / Question mark replaces period for questions / Exclamation point replaces period for exclamationsCore Uses
| Sentence type | End punctuation | Example |
|---|---|---|
| Declarative — statement of fact or opinion | period | The results confirmed the hypothesis. |
| Imperative — instruction or request | period (mild) / ! (emphatic) | Please submit the report by Friday. / Stop! |
| Indirect question — question embedded in a statement | period (NOT question mark) | She asked whether the results were ready. |
| Rhetorical question used as statement | period (stylistic choice) | One has to wonder whether the policy was effective. |
Periods in Abbreviations
| Abbreviation type | British style | American style |
|---|---|---|
| Title — last letter same as full word (Dr, Mr, St) | no period: Dr Ahmed, Mr Osei, St James | period: Dr. Ahmed, Mr. Osei, St. James |
| Title — last letter differs (Prof., Capt.) | period: Prof. Chen | period: Prof. Chen |
| Latin abbreviations | period: e.g., i.e., etc. | period: e.g., i.e., etc. |
| Acronyms / initialisms | no period: BBC, NASA, PhD | often no period: BBC, NASA, PhD |
Period vs Other End Punctuation
| Sentence | Correct end punctuation | Why |
|---|---|---|
| The meeting is on Thursday | period | statement of fact |
| Is the meeting on Thursday | question mark | direct question |
| She asked if the meeting was on Thursday | period | indirect question embedded in statement |
| What a thorough report | exclamation point or period | exclamation — stronger with !, milder with . |
Key Period Contexts
Indirect questions end with a period, not a question mark
An indirect question reports a question as a statement. It uses statement word order (subject + verb) and ends with a period. The most common error is adding a question mark because the content is a question, but the sentence itself is a statement.
- Direct question: Are the results ready?
- Indirect question: She asked whether the results were ready.
- Direct question: What time does the meeting start?
- Indirect question: He wanted to know what time the meeting started.
One period at end of sentence — not two
When a sentence ends with an abbreviation that takes a period (etc., Dr., U.S.A.), only one period appears — the abbreviation period serves as the sentence-ending period too. Do not add a second period after the first.
- Correct: The package contained a pen, a notebook, a stapler, etc.
- Incorrect: The package contained a pen, a notebook, a stapler, etc..
- Correct: She works for the U.S. Department of Education.
Period Warning Signals
Direct Question vs Indirect Question
The sentence type — not the content — determines the end punctuation. A sentence containing a question as a subordinate clause is a statement and ends with a period.
Direct question — question mark
What caused the discrepancy in the data?
The sentence itself is a question — it ends with a question mark.
Indirect question — period
The analyst investigated what caused the discrepancy in the data.
The question is embedded as a subordinate clause. The sentence is a statement — it ends with a period.
Common Mistakes
Question mark after an indirect question
✗ She asked whether the deadline had been extended?
She asked whether the deadline had been extended.
An indirect question is a statement, not a direct question. It ends with a period. The question mark belongs only at the end of direct questions.
Two periods when a sentence ends with an abbreviation
✗ Bring your passport, boarding pass, etc..
Bring your passport, boarding pass, etc.
When a sentence ends with an abbreviation period, that period also ends the sentence. One period does both jobs.
Period inside quotation marks in British style when not part of the original
✗ The document was described as 'groundbreaking.'
The document was described as 'groundbreaking'.
In British English, the period goes outside the closing quotation mark when it belongs to the containing sentence, not the quotation.
No period after mild imperatives
✗ Please review the attached document
Please review the attached document.
Mild imperatives (requests and instructions) end with a period unless they are emphatic, in which case an exclamation point is used.
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