Proofreader
Overview
This skill catches grammar errors, spelling mistakes, punctuation problems, inconsistent style, and tone mismatches in any written content—emails, reports, blog posts, essays, or marketing copy. It distinguishes between proofreading (surface-level errors) and copy editing (structural issues), applies common style guide rules, and flags commonly confused words. The output is a corrected version of the text with explanations of changes, or a marked-up list of issues depending on your preference.
When to Use
- Final review before publishing a blog post or article
- Checking an important email before sending
- Reviewing a business report or proposal for errors
- Polishing an essay or academic paper
- Auditing marketing copy for consistency and tone
- Verifying consistency in longer documents (capitalization, hyphenation, terminology)
When NOT to Use
- When the content needs to be restructured, reorganized, or substantially rewritten (that's developmental or copy editing)
- When the content is a rough draft that hasn't been reviewed by the author yet—proofread the near-final version
- For technical accuracy checking (confirming facts, code correctness, data)
- When you need a completely new version of the content
Quick Reference
| Task |
Approach |
| Grammar |
Check subject-verb agreement, tense consistency, dangling modifiers |
| Punctuation |
Oxford comma, em dash usage, apostrophes, semicolons |
| Commonly confused |
affect/effect, its/it's, their/there/they're, that/which, who/whom |
| Style consistency |
Capitalization, hyphenation, number formatting, terminology |
| Tone check |
Formal/casual match, second-person consistency, active/passive balance |
| Markup |
Strikethrough deleted text, bold/bracket insertions |
Instructions
Clarify the style guide and tone. Before proofreading, establish:
- Style guide: AP, Chicago, MLA, APA, or house style?
- Audience tone: formal, professional-casual, or informal?
- Any document-specific conventions (e.g., always capitalize "Team" when referring to the product)?
Read for meaning first, errors second. On the first pass, read the entire piece to understand what it's trying to say. This prevents "correcting" deliberate stylistic choices.
Check grammar systematically. Focus on:
- Subject-verb agreement: "The data show" (data is plural) vs. "The data shows"
- Tense consistency: Don't switch between past and present within the same section
- Dangling modifiers: "Having finished the report, the coffee was cold." (Who finished the report? Not the coffee.)
- Sentence fragments: Incomplete sentences without a main verb
- Run-on sentences: Two independent clauses joined without proper punctuation
Check punctuation.
- Oxford comma: "We invited the manager, the developer, and the designer." (Use unless house style forbids it)
- Apostrophes: Possessives (it's = it is; its = possessive), plurals never get apostrophes
- Em dashes vs. en dashes: Em dash (—) for breaks in thought; en dash (–) for ranges (2019–2023)
- Semicolons: Connect two complete, related independent clauses
- Comma splices: "I finished the report, it looked great." → Use a period, semicolon, or conjunction
Flag commonly confused words:
| Confused Pair |
Rule |
| affect / effect |
Affect = verb (to influence); Effect = noun (the result) |
| its / it's |
its = possessive; it's = it is |
| their / there / they're |
possessive / location / they are |
| that / which |
"that" restricts (no comma); "which" adds info (comma before it) |
| who / whom |
who = subject; whom = object |
| fewer / less |
fewer = countable; less = uncountable |
| lay / lie |
lay = to place something; lie = to recline |
| complement / compliment |
complement = completes; compliment = praise |
| principal / principle |
principal = main/head person; principle = rule/value |
| further / farther |
farther = physical distance; further = metaphorical |
Check style consistency throughout the document:
- Capitalization: Is "Director" always capitalized? Or never?
- Numbers: Spell out one through nine, numerals for 10+? Or always numerals?
- Hyphenation: "email" or "e-mail"? "decision-maker" or "decision maker"?
- Serial comma: used consistently throughout?
- Terminology: Same word used for the same concept every time?
Check tone and register.
- Does the formality level match the audience and context?
- Is second-person ("you") used consistently where applicable?
- Are there shifts from active to passive that weaken the writing?
- Does the tone stay consistent, or does it veer between professional and overly casual?
Output format. Choose one:
- Corrected version: Full rewritten text with all errors fixed (best for clean final copy)
- Marked-up version: Original text with inline corrections using conventions (best for showing what changed)
- Error report: Bulleted list of issues with original → corrected for each (best for learning/feedback)
Examples
Example 1: Proofreading a Business Report Paragraph
Input:
"The team have successfully completed the Q3 objectives, which was a significant achievement given the projects complexity. Going forward, we need to focus on improving our response times, their currently averaging 48 hours which effects customer satisfaction scores. Its important that each team member understand there role in achieving this target by years end."
Output:
Corrected Version:
"The team has successfully completed the Q3 objectives, which was a significant achievement given the project's complexity. Going forward, we need to focus on improving our response times—they're currently averaging 48 hours, which affects customer satisfaction scores. It's important that each team member understands their role in achieving this target by year's end."
Changes Made:
- "have → has" — "team" is treated as a singular collective noun in American English
- "projects → project's" — possessive requires apostrophe
- "their → they're" — contraction of "they are"
- "which effects → which affects" — "affects" (verb) is correct here; "effect" would be the noun
- "Its → It's" — contraction of "it is"
- "understand → understands" — subject "each team member" is singular
- "there → their" — possessive pronoun for "their role"
- "years end → year's end" — possessive requires apostrophe
- Added em dash before "they're" to improve flow and separate the clause clearly
Example 2: Proofreading a Professional Email
Input:
"Hi Marcus,
Thanks for meeting with myself and Sarah yesterday, we really enjoyed the conversation. Going forward I think theirs a real opportunity here for both our organizations. We would love to setup a more formal call to discuss the specifics of the proposal that was presented by you.
Looking forward to hearing your thoughts,
Jennifer"
Output:
Corrected Version:
"Hi Marcus,
Thanks for meeting with Sarah and me yesterday—we really enjoyed the conversation. Going forward, I think there's a real opportunity here for both of our organizations. We'd love to set up a more formal call to discuss the specifics of your proposal.
Looking forward to hearing your thoughts,
Jennifer"
Changes Made:
- "myself and Sarah → Sarah and me" — "myself" is reflexive and only correct when the subject is "I" (e.g., "I did it myself"). "Me" is the object form. Conventionally, put yourself last.
- "yesterday, we → yesterday—we" — Comma splice fixed with em dash for better flow
- "Going forward I → Going forward, I" — Introductory phrase needs a comma
- "theirs → there's" — Contraction of "there is"
- "both our → both of our" — More natural phrasing
- "setup → set up" — "setup" is a noun; the verb phrase is "set up"
- "the proposal that was presented by you → your proposal" — Active voice; removes wordiness
Best Practices
- Proofread in a different medium than you wrote—print it out, or change the font size; errors become more visible
- Read backwards (last sentence to first) to catch spelling errors your brain auto-corrects when reading for meaning
- Proofread in multiple focused passes: one for grammar, one for punctuation, one for style consistency
- Take a break between writing and proofreading—fresh eyes catch more
- For long documents, proofread in sections, not in one marathon session
- Use text-to-speech to hear the text; awkward phrasing is easier to detect by ear
Common Mistakes
- Correcting intentional style choices: Some fragments and comma breaks are deliberate—confirm before "fixing"
- Over-correcting to formal: If the original tone is casual and appropriate, don't stiffly formalize it
- Missing errors at page/section breaks: Attention naturally resets; these transitions need extra scrutiny
- Not checking headers and captions: These are often proofread last (or not at all) and contain errors
- Skipping numbers and data: Wrong dates, percentages, and figures slip through when proofreaders focus on prose
- Fixing the same error inconsistently: If "e-mail" appears 10 times and you change it to "email", change all 10
Tips & Tricks
- Use the "CMOS test" for who/whom: substitute he/him. If "he" sounds right, use "who"; if "him" sounds right, use "whom"
- For affect/effect: Remember "RAVEN" — Remember Affect Verb Effect Noun
- Check whether the document uses one space or two after periods—it should be consistent (one is the modern standard)
- Confirm that all headers are parallel in structure (all noun phrases, or all imperative verbs, not a mix)
- In formal documents, verify that all abbreviations are spelled out on first use: "artificial intelligence (AI)"
- Search-and-replace is your friend for consistency: find every instance of "email" to ensure uniform spelling
Related Skills
1---
2name: proofreader
3description: 'Use this skill when reviewing written content for grammar, spelling, punctuation, style consistency, and tone—before publishing, submitting, or sending. Trigger phrases: ''proofread this'', ''check my writing'', ''review this for errors'', ''edit this email/report/essay''. Do NOT use when structural rewrites or content changes are needed—proofreading fixes surface errors, not substantive problems.'
4version: 1.0.0
5author: community
6tags:
7 - writing
8 - proofreading
9 - editing
10 - grammar
11license: MIT
12keywords:
13 - proofread
14 - grammar check
15 - spelling
16 - editing
17 - proofreader
18---
19
20# Proofreader
21
22## Overview
23This skill catches grammar errors, spelling mistakes, punctuation problems, inconsistent style, and tone mismatches in any written content—emails, reports, blog posts, essays, or marketing copy. It distinguishes between proofreading (surface-level errors) and copy editing (structural issues), applies common style guide rules, and flags commonly confused words. The output is a corrected version of the text with explanations of changes, or a marked-up list of issues depending on your preference.
24
25## When to Use
26- Final review before publishing a blog post or article
27- Checking an important email before sending
28- Reviewing a business report or proposal for errors
29- Polishing an essay or academic paper
30- Auditing marketing copy for consistency and tone
31- Verifying consistency in longer documents (capitalization, hyphenation, terminology)
32
33## When NOT to Use
34- When the content needs to be restructured, reorganized, or substantially rewritten (that's developmental or copy editing)
35- When the content is a rough draft that hasn't been reviewed by the author yet—proofread the near-final version
36- For technical accuracy checking (confirming facts, code correctness, data)
37- When you need a completely new version of the content
38
39## Quick Reference
40| Task | Approach |
41|------|----------|
42| Grammar | Check subject-verb agreement, tense consistency, dangling modifiers |
43| Punctuation | Oxford comma, em dash usage, apostrophes, semicolons |
44| Commonly confused | affect/effect, its/it's, their/there/they're, that/which, who/whom |
45| Style consistency | Capitalization, hyphenation, number formatting, terminology |
46| Tone check | Formal/casual match, second-person consistency, active/passive balance |
47| Markup | Strikethrough deleted text, bold/bracket insertions |
48
49## Instructions
50
511. **Clarify the style guide and tone.** Before proofreading, establish:
52 - Style guide: AP, Chicago, MLA, APA, or house style?
53 - Audience tone: formal, professional-casual, or informal?
54 - Any document-specific conventions (e.g., always capitalize "Team" when referring to the product)?
55
562. **Read for meaning first, errors second.** On the first pass, read the entire piece to understand what it's trying to say. This prevents "correcting" deliberate stylistic choices.
57
583. **Check grammar systematically.** Focus on:
59 - **Subject-verb agreement:** "The data show" (data is plural) vs. "The data shows"
60 - **Tense consistency:** Don't switch between past and present within the same section
61 - **Dangling modifiers:** "Having finished the report, the coffee was cold." (Who finished the report? Not the coffee.)
62 - **Sentence fragments:** Incomplete sentences without a main verb
63 - **Run-on sentences:** Two independent clauses joined without proper punctuation
64
654. **Check punctuation.**
66 - **Oxford comma:** "We invited the manager, the developer, and the designer." (Use unless house style forbids it)
67 - **Apostrophes:** Possessives (it's = it is; its = possessive), plurals never get apostrophes
68 - **Em dashes vs. en dashes:** Em dash (—) for breaks in thought; en dash (–) for ranges (2019–2023)
69 - **Semicolons:** Connect two complete, related independent clauses
70 - **Comma splices:** "I finished the report, it looked great." → Use a period, semicolon, or conjunction
71
725. **Flag commonly confused words:**
73 | Confused Pair | Rule |
74 |---------------|------|
75 | affect / effect | Affect = verb (to influence); Effect = noun (the result) |
76 | its / it's | its = possessive; it's = it is |
77 | their / there / they're | possessive / location / they are |
78 | that / which | "that" restricts (no comma); "which" adds info (comma before it) |
79 | who / whom | who = subject; whom = object |
80 | fewer / less | fewer = countable; less = uncountable |
81 | lay / lie | lay = to place something; lie = to recline |
82 | complement / compliment | complement = completes; compliment = praise |
83 | principal / principle | principal = main/head person; principle = rule/value |
84 | further / farther | farther = physical distance; further = metaphorical |
85
866. **Check style consistency throughout the document:**
87 - Capitalization: Is "Director" always capitalized? Or never?
88 - Numbers: Spell out one through nine, numerals for 10+? Or always numerals?
89 - Hyphenation: "email" or "e-mail"? "decision-maker" or "decision maker"?
90 - Serial comma: used consistently throughout?
91 - Terminology: Same word used for the same concept every time?
92
937. **Check tone and register.**
94 - Does the formality level match the audience and context?
95 - Is second-person ("you") used consistently where applicable?
96 - Are there shifts from active to passive that weaken the writing?
97 - Does the tone stay consistent, or does it veer between professional and overly casual?
98
998. **Output format.** Choose one:
100 - **Corrected version:** Full rewritten text with all errors fixed (best for clean final copy)
101 - **Marked-up version:** Original text with inline corrections using conventions (best for showing what changed)
102 - **Error report:** Bulleted list of issues with original → corrected for each (best for learning/feedback)
103
104## Examples
105
106### Example 1: Proofreading a Business Report Paragraph
107
108**Input:**
109"The team have successfully completed the Q3 objectives, which was a significant achievement given the projects complexity. Going forward, we need to focus on improving our response times, their currently averaging 48 hours which effects customer satisfaction scores. Its important that each team member understand there role in achieving this target by years end."
110
111**Output:**
112
113**Corrected Version:**
114"The team has successfully completed the Q3 objectives, which was a significant achievement given the project's complexity. Going forward, we need to focus on improving our response times—they're currently averaging 48 hours, which affects customer satisfaction scores. It's important that each team member understands their role in achieving this target by year's end."
115
116**Changes Made:**
1171. "have → has" — "team" is treated as a singular collective noun in American English
1182. "projects → project's" — possessive requires apostrophe
1193. "their → they're" — contraction of "they are"
1204. "which effects → which affects" — "affects" (verb) is correct here; "effect" would be the noun
1215. "Its → It's" — contraction of "it is"
1226. "understand → understands" — subject "each team member" is singular
1237. "there → their" — possessive pronoun for "their role"
1248. "years end → year's end" — possessive requires apostrophe
1259. Added em dash before "they're" to improve flow and separate the clause clearly
126
127---
128
129### Example 2: Proofreading a Professional Email
130
131**Input:**
132"Hi Marcus,
133
134Thanks for meeting with myself and Sarah yesterday, we really enjoyed the conversation. Going forward I think theirs a real opportunity here for both our organizations. We would love to setup a more formal call to discuss the specifics of the proposal that was presented by you.
135
136Looking forward to hearing your thoughts,
137Jennifer"
138
139**Output:**
140
141**Corrected Version:**
142"Hi Marcus,
143
144Thanks for meeting with Sarah and me yesterday—we really enjoyed the conversation. Going forward, I think there's a real opportunity here for both of our organizations. We'd love to set up a more formal call to discuss the specifics of your proposal.
145
146Looking forward to hearing your thoughts,
147Jennifer"
148
149**Changes Made:**
1501. "myself and Sarah → Sarah and me" — "myself" is reflexive and only correct when the subject is "I" (e.g., "I did it myself"). "Me" is the object form. Conventionally, put yourself last.
1512. "yesterday, we → yesterday—we" — Comma splice fixed with em dash for better flow
1523. "Going forward I → Going forward, I" — Introductory phrase needs a comma
1534. "theirs → there's" — Contraction of "there is"
1545. "both our → both of our" — More natural phrasing
1556. "setup → set up" — "setup" is a noun; the verb phrase is "set up"
1567. "the proposal that was presented by you → your proposal" — Active voice; removes wordiness
157
158---
159
160## Best Practices
161- Proofread in a different medium than you wrote—print it out, or change the font size; errors become more visible
162- Read backwards (last sentence to first) to catch spelling errors your brain auto-corrects when reading for meaning
163- Proofread in multiple focused passes: one for grammar, one for punctuation, one for style consistency
164- Take a break between writing and proofreading—fresh eyes catch more
165- For long documents, proofread in sections, not in one marathon session
166- Use text-to-speech to hear the text; awkward phrasing is easier to detect by ear
167
168## Common Mistakes
169- **Correcting intentional style choices:** Some fragments and comma breaks are deliberate—confirm before "fixing"
170- **Over-correcting to formal:** If the original tone is casual and appropriate, don't stiffly formalize it
171- **Missing errors at page/section breaks:** Attention naturally resets; these transitions need extra scrutiny
172- **Not checking headers and captions:** These are often proofread last (or not at all) and contain errors
173- **Skipping numbers and data:** Wrong dates, percentages, and figures slip through when proofreaders focus on prose
174- **Fixing the same error inconsistently:** If "e-mail" appears 10 times and you change it to "email", change all 10
175
176## Tips & Tricks
177- Use the "CMOS test" for who/whom: substitute he/him. If "he" sounds right, use "who"; if "him" sounds right, use "whom"
178- For affect/effect: Remember "RAVEN" — Remember Affect Verb Effect Noun
179- Check whether the document uses one space or two after periods—it should be consistent (one is the modern standard)
180- Confirm that all headers are parallel in structure (all noun phrases, or all imperative verbs, not a mix)
181- In formal documents, verify that all abbreviations are spelled out on first use: "artificial intelligence (AI)"
182- Search-and-replace is your friend for consistency: find every instance of "email" to ensure uniform spelling
183
184## Related Skills
185- [blog-post](../../writing/blog-post/SKILL.md)
186- [email-drafter](../../writing/email-drafter/SKILL.md)
187- [academic-essay](../../writing/academic-essay/SKILL.md)
188- [technical-writer](../../writing/technical-writer/SKILL.md)