Discovering that pages need basic copyediting, i.e. correcting for grammar, spelling, readability, or layout, may surprise new visitors to Wikipedia, but this is the "encyclopedia that anyone can edit": it is not perfect! Thousands of articles need simple improvements you can make without being an expert in the subject. Copyediting involves the "five Cs": making the article clear, correct, concise, comprehensible, and consistent. The following is a guide for new copyeditors.
Scan the article for errors or ways in which it can be improved. The entire article or particular sections may be tagged as needing a copyedit. There is a list of common mistakes below.
Edit the page by clicking the "Edit" or "Edit source" tab near the top of it or one of the section [edit source] links.
Make your changes and fill out an edit summary. Be helpful to the editors who follow you by giving a summary of what you have done. Simple "Copy edit" is fine, but "Edited for tone" is even better. The most commonly used abbreviation for "copy edit" is "ce".
Preview your change and save.
Step five (optional)
If you think the article does not need further basic copyediting, click Edit again and remove the "copy edit" template at the top of the article, which is what flags it as needing improvement. The template typically is markup that looks like ((copy edit)), with a date inside the braces.
Common mistakes to fix
Grammarly and LanguageTool have free plugins for popular web browsers that check spelling, grammar, usage, and punctuation.
Titles of works of art (paintings, sculpture), plays and operas, television series, films, novels and nonfiction books, song cycles, and long poems should be italicized rather than put in quotation marks, e.g. Zen and the Art of Motorcycle Maintenance.
Avoid affected, pompous, or excessive language, e.g. "due to the fact that" for "because", "ascertain the location of" for "find", and (in almost all cases) "utilize" for "use".
Check articles for unnecessary words and redundant phrases. Vigorous, effective writing is clear and concise. See Plain English.
Quotations should not be changed, except for trivial spelling and typographic errors. Otherwise, obvious errors and censorship in the original can be marked with ((sic)), which displays as [sic]. Legitimate insertions and omissions are acceptable if marked by square brackets and ellipses, respectively. See WP:MOSQUOTE for details.
Be careful to use the correct variety of English (e.g. American vs. British), which affects spelling (e.g. flavour, colour, centre and defence vs. flavor, color, center, and defense). Wikipedia:Manual of Style § National varieties of English has extensive guidance on how to choose correctly and how to write clearly for all readers.
Articles about a given region use that region's variety of English.
Otherwise, the first variety used by any given editor is retained by the succeeding editors.
The talk page may have a banner clarifying which variety is already established, or the article may have a template like ((Use British English)) at the top of the wikitext.
Most web browsers have built-in spell-checking, or you can use external websites or software to check for possible errors.
If you want to focus on misspellings only, these tools are handy:
Remember that Wikipedia is a collaborative, consensus-based environment. Be bold in making changes, but if you find that your work has been undone by another editor, visit the talk page of the article and start a discussion before reinstating it.
According to Butcher's Copy-editing, "The good copyeditor is a rare creature: an intelligent reader and a tactful and sensitive critic; someone who cares enough about perfection of detail to spend time checking small points of consistency in someone else's work but has the good judgement not to waste time or antagonize the author by making unnecessary changes."
Articles in need of basic copyediting may be tagged with templates such as ((copyedit)) or ((copyedit-section)). A list of such articles can be found in a few places. The easiest places to get started are: