Definition · Plain-language
English grammar rules
A concise reference to the most important English grammar rules — covering subject-verb agreement, verb tenses, pronouns, punctuation, sentence structure and common confusables — useful for both native speakers and ESL/EFL learners.
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The foundational rules: agreement, tense and pronouns
Subject-verb agreement is the rule that produces the most errors: the verb must match its grammatical subject in number, not the nearest noun. "The impact of the changes has been significant" — subject is impact, verb is has. Verb tense consistency means you should not shift tense without a logical reason: a paragraph in the past tense should stay in the past tense. The present tense is used for general truths and for discussing published works ("Smith (2023) argues that…"). Pronoun agreement requires every pronoun to match its antecedent in number and, where relevant, gender. "Each participant submitted their consent form" uses singular they, now standard. Pronoun case: use subject forms (I, he, she, who) when the pronoun is the subject of a clause; use object forms (me, him, her, whom) when it is an object or follows a preposition.
Punctuation rules: commas, apostrophes and sentence boundaries
Commas: use after introductory elements; before co-ordinating conjunctions joining independent clauses; around non-restrictive relative clauses; and before the final item in a list (Oxford comma). Avoid the comma splice — using a comma alone to join two independent clauses. Apostrophes: add 's for singular possession (the author's argument), apostrophe alone for plural nouns ending in s (the authors' findings), and 's for irregular plurals (children's rights). Use apostrophes in contractions (it's = it is) but never for simple plurals (1990s, CDs). Sentence boundaries: every sentence must have at least one independent clause. A dependent clause standing alone is a fragment ("Because the data were incomplete." — error). Two independent clauses without a separator produce a run-on sentence, and two joined by only a comma produce a comma splice — both are errors corrected by a semicolon, a co-ordinating conjunction, or a full stop.
Modifiers, parallel structure, articles and British vs American differences
Modifier placement: place adjectives and adverbs immediately before or after the word they modify. A misplaced modifier creates ambiguity; a dangling modifier has no referent at all. Parallel structure: items in a list, comparisons and paired constructions must have the same grammatical form (running, cycling and swimming — not running, cycling and to swim). Articles: use a before a consonant sound (a university), an before a vowel sound (an hour — the h is silent); use the for specific or previously mentioned nouns. British and American English differ in several grammar conventions: British English may take plural verbs with collective nouns (the team are); American English does not. Spelling differences (recognise/recognize, practise/practice, colour/color) are matters of orthography, not grammar. On either side of the Atlantic, the core grammar rules above remain the same.
Key facts
At a glance
- Subject-verb agreement: verb matches the grammatical subject in number
- Tense consistency: do not shift tenses without logical reason
- Pronoun agreement: pronoun matches antecedent in number (singular they is standard)
- Comma splice: joining two independent clauses with only a comma is an error
- Apostrophes: possession and contractions only — never for plurals
- Sentence fragment: a dependent clause standing alone is an error
- Modifier placement: adjacent to the word it modifies; misplaced or dangling modifiers cause ambiguity
- Parallel structure: list items, comparisons and correlative pairs must share the same grammatical form
Common misconceptions
What people often get wrong
Often heard: English grammar rules are the same in British and American English.
Actually: Most core rules are shared, but there are differences: collective nouns may take plural verbs in British English but singular in American English; some preposition and tense choices also differ (have got vs have gotten; at the weekend vs on the weekend).
Often heard: If you can understand the meaning, the grammar does not matter.
Actually: In formal academic, professional and published writing, grammatical accuracy matters for credibility and precision. Errors in agreement, modifier placement or sentence boundaries can alter meaning or signal carelessness to readers and editors.
Often heard: Grammar rules never change.
Actually: English grammar is descriptive as well as prescriptive. Usage evolves: singular they was once labelled informal and is now standard; ending a sentence with a preposition was once discouraged but is now widely accepted. Authoritative style guides update regularly.
Going deeper
