The Editor’s Manual
Free learning resource on English grammar, punctuation, usage, and style.
Prepositions with overlapping meanings: In/into/inside/within, in/during, for/since, on/upon/onto, over/above, over/more than, under/less than, below/beneath/under/underneath, off/of, beside/besides, round/around, to/toward/towards.
Use commas to make lists, set off phrases, separate clauses, and indicate that a detail is nonessential in a sentence.
Avoid using an apostrophe before the “s” in a plural, unless not using one would result in confusion (e.g., two “i’s” in “iridescent”).
Collective nouns such as “team” are treated as singular in American but plural in British English. It also depends on whether you want to refer to the group as a whole or to the individual members of the group.
Data can be a plural noun (“the data are”) or a singular mass noun (“the data is”). As a mass noun, it is used much like the word “information.”
Use “who” for the subject and “whom” for the object in a sentence. In everyday communication, “who” can replace “whom.” To choose between “who” and “whom,” a simple trick is to form a question and frame its answer.
The word “effect” is used most often as a noun, and “affect” most often as a verb: when you affect something, you have an effect on it.