Having corrected the English of students of many nationalities and handwritings, copyediting is a doddle/aesthetic imperative/primal urge. Many of my edits are difficult to spot in "diffs" as they involve inconspicuous punctuation changes, closing spaces before refs, etc., though I often feel the need to improve a lead (or "lede", from the Greek ληδη). I've also rescued a few good paragraphs discarded in the process of reverting vandalism; it's quite easy to paste from "diffs".
Wikipedia is mostly a static, text medium, so its model should be print, not television or even other websites. Thus, I
close unsightly spaces, as, for example, round the em dash (a spaced em dash means that there is a — missing), stroke/slash/solidus (they're thin and slanted so as to make spaces unnecessary—space savers, not space creators), unquoted ellipsis, or hyphen/en dash in the case of years (1234–1432), but not where the hyphen - here - is being used as a dash—though an em dash – or en – cuts more of a dash—nor, for clarity, between days (1 January 1234 – 31 December 2345).
remove bracket clashes in running prose (this kind of thing:) (ugh!), which would never be acceptable in a print publication (people are used to seeing them in Wikipedia lists), and replace them, usually with a semicolon (like this; that's better). (See PAIS Alliance for a good example of how to format a complex lead.)
deplore the foolish practice of changing date formats between so-called American and British. Both styles are correct in both varieties of English (the Fourth of July, for example) and I never encountered this false distinction in pre-Wikipedian times, though omitting the article in speech ('July fifth') is distinctly American. Similarly, there is no point in fastidiously standardising the date format throughout an article: it is not a matter of spelling. (But when the year is mentioned I do prefer to put the day first: it's more logical and avoids commas—and logical dates go with logical quotes.) A real, and very common, mistake, though, is attempting to balance 'from' with a dash: 'from 1950–2010' means from that period to another, unstated time, but usually the intended meaning is 'from 1950 to 2010'.
remove Incorrect or Unnecessary Capital Letters like These, unquestionably Wikipedia's number one mistake (and that apart from the fact that not everyone has noticed that we have the compulsory luxury of sentence case in headings). Proper capitalisation is important to distinguish the general from the particular: the Earth goes round the Sun, and if there's too much sun the earth dries out and develops cracks. Fans of different types of music often mistakenly capitalise them, from jazz to jungle, probably because of the names of music charts ("#51 Country", etc.). There are those who capitalise the names of currencies, probably because many of them sound like proper nouns: franc, for example, or mark (though those two have now vacated the scene—almost—in favour of the equally capitalised-sounding euro). Some people seem to capitalise words just because they've never seen or heard them before. Sometimes there are contentious examples: I'm happy to have been on the winning side in the case of trojan moonsand asteroids. (Single and singly hyphenated letters are capitalised, however: an X, T-shirt, B-side.)
And then there is the word the in running prose. This was voted on in the case of the Beatles; uncapitalised "the" beat capitalised, but only by 2–1. A capital T is necessary when referring to the article about a band, as in "See The Beatles", but I suspect the real reason people are obsessed with it is its use in titles, e.g. The Great Gatsby. Titles have the capital, names don't. Other items apart from pop groups should have lower case too, such as the Troubles. The policy is detailed here. (Incidentally, thanks to Wikipedia, I now know that the Beatles officially ceased to be Beatles on the day I ceased to be a teenager.)
Three more things I do: insert compound-attributive-adjective-clarifying hyphens; supply post-parenthetical commas, especially after locations of locations, as for example in "A hotel in Mecca, Saudi Arabia collapses"; and normalise meaningless hard-on-the-eye magazine-style chunks of italics.
however—where it is too strong (an adverb, not a conjunction) and needs changing to but or though. The misuse is usually advertised by the lack of a comma after it: "She likes cats, however she doesn't like dogs" instead of "but she doesn't like dogs". (When this "however" is the right word beginning a sentence, a comma will help distinguish it from "However many/often/hard...". Compare "however, it was done" with "however it was done...", the latter meaning "in whatever way it was done").
would, especially in music articles, as narrative-style padding instead of the simple past tense: "In June they would release their 94th album".
likely used as an adverb, as in "some of these stars likely have Earth-like planets", an American colloquialism. True, there aren't too many synonyms of "probably", but, used formally, "likely" is an adjective, a synonym of "probable" ("a likely story") though with wider usage ("they are likely to have planets") and this is its only use in British English and formal American. (The man who finds the planets, the US astronomer Mike Brown, grades these terms with weird precision, so that "are likely to be" is more probable than "are probably".)
multiple, the latest substitute for many, and particularly clunky.
I try not to worry too much about American spelling in a British context and vice versa. The trouble with Noah (the man with the US dictionry, sorry, U.S. dictionerry) is he didn't go far enough, and American spelling remains just as daft as British. (And punctuation just daft.)
At Citizendium I wrote a complete set of articles on English spelling and pronunciation, using the actual spelling instead of the International Phonetic Alphabet, and including a word list in retroalphabetical order. I invented this system: sát, mâde, pàrk, cāst, åll, ãir; sét, mê, vèin, fërn; sít, mîne, skì, bïrd; sóng, môde, moôn, lòve, foòt, wörd, ŏr; sún, mûse, fùll, pürr; neŵ, ẁant; gým, mŷ, keỳ, mÿrrh.
British pronunciations under threat: ámateur (-tə, AmE -chr), hárass (AmE haráss), prívacy (AmE prîvacy, cf. prîvate), resëarch (AmE rêsearch); word under threat: queûe, pronounced like cûe, meaning (to be part of) a line of waiting people.
When Brian Johnston said it on BBC radio's Test Match Special, I was watching television with the sound turned down, as one did, and, while the commentators giggled uncontrollably, I thought that much more often Holding would be bowling to Willey, fast bowler to all-rounder. It didn't occur to me that history would rewrite it, with Johnston himself reversing them in his autobiography, apparently, and others even claiming the story was apocryphal.
So, when the sources are unreliable, Wikipedia doesn't stand a chance.
^This was a "Pilz records" disambiguation page, but was deleted and redirected to the German label. I mention it here because I have two jazz CDs on a mysterious American Pilz (Entertainment, Inc.) label.
^This ugly spacing ( / ) mirrors advertising, TV, website headings, etc., where commas may be felt to be insufficiently eye-catching. The spaced slash in prose is traditionally used only to indicate line breaks when quoting the non-prose of poems and songs. Here, people sometimes use spaces in prose cases that involve items of more than one word on either side of the slash, but these should be separated with commas or conjunctions, or where appropriate an ampersand (&) instead.
^And the morons who change the long-established 'AD' and 'BC' to the repetitive and longer 'CE' and 'BCE'—as if the former were some kind of profession of faith—deserve no more than a footnote.
To my dear teacher Rothorpe. Whilst flicking through your user page, I was horrified to see that I have never given you a star, especially when I think of the many times you have helped me and my FAC's, such as here. Thank you for all you do and for correcting my many mistakes. Cassiantotalk 11:28, 9 May 2014 (UTC)
The Random Acts of Kindness Barnstar
Being in a good mood and feeling the urge to do something nice, I give you this barnstar that you earned every day w/o ever losing your temper like I and most editors have done on a regular basis. You always behave like an angel and I don't know how you do it in this crazy environment.TMCk (talk) 02:33, 23 September 2013 (UTC)
The Copyeditor's Barnstar
Many, many thanks for your constant work on Terry-Thomas. Both Cassianto and I are extremely grateful for your diligent attention! All the best - SchroCat (talk) 15:25, 8 July 2013 (UTC)
The motto of the AIW is Conservata veritate, which translates to, "With the preserved truth".
This motto reflects the inclusionist desire to change Wikipedia only when no knowledge would be lost as a result.