Most people think of themselves as grammar rebels, seeing the rules as strict, basic and arbitrary. But grammar is actually complex, not to mention essential: Incorrect grammar can cause confusion and change the way you’re perceived (or even keep you from landing a job).
That’s why a grammar checker is essential if writing is part of your workday — even if that’s just sending emails. Here’s what else you should know about grammar:
What is grammar in English?
At a high level, the definition of grammar is a system of rules that allow us to structure sentences. It includes several aspects of the English language, like:
Parts of speech (verbs, adjectives, nouns, adverbs, prepositions, conjunctions, modifiers, etc.)
Clauses (e.g. independent, dependent, compound)
Punctuation (like commas, semicolons, and periods — when applied to usage)
Mechanics of language (like word order, semantics, and sentence structure)
Grammar’s wide scope can make proofreading difficult. And the dry, academic conversations that often revolve around it can make people’s eyes glaze over. But without these grammatical rules, chaos would ensue. So even if you aren’t a fan (and who really is?), it’s still important to understand.

Types of grammar (and theories)
As long as there have been rules of grammar, there have been theories about what makes it work and how to classify it. For example, American linguist Noam Chomsky posited the theory of universal grammar. It says that common rules dictate all language.
In his view, humans have an innate knowledge of language that informs those rules. That, he reasoned, is why children can pick up on complex grammar without explicit knowledge of the rules. But grammarians still debate about whether this theory holds true.
There are also prescriptive and descriptive grammar types:
Prescriptive grammar is the set of rules people should follow when using the English language.
Descriptive grammar is how we describe the way people are using language.
Another theory emerges from these types of English grammar: primacy of spoken language. It says language comes from the spoken word, not writing — so that’s where you’ll find answers to what’s grammatically correct. Though not everyone agrees with that theory, either.
How did grammar become what it is today?
Grammar has been in a constant state of evolution, starting with the creation of the first textbook on the subject in about 100 BC by the Greeks (termed the Greek grammatikē). The Romans later adapted their grammar to create Latin grammar (or Latin grammatica), which spread out across Europe to form the basis for languages like Spanish and French. Eventually, Latin grammar became the basis of the English model in the 11th century. The rules of grammar (as well as etymology) changed with the times, from Middle English in the 15th century, to what we know today.
Another consequence of grammatical changes has been the development of various areas of linguistic study, like phonology (how languages or dialects organize their sounds) and morphology (how words are formed how and their relationships work).
The ancient grammar rules have changed as people have tested alternative ways to use language. Authors, for example, have broken the rules to various levels of success:
- Shakespeare ended sentences with prepositions: “Fly to others that we know not of.”
- Jane Austen used double negatives: “When Mr. Collins said any thing of which his wife might reasonably be ashamed, which certainly was not unseldom, she involuntarily turned her eye on Charlotte.”
- William Faulkner started sentences with conjunctions: “But before the captain could answer, a major appeared from behind the guns.”
Cultural norms shape grammar rules, too. The Associated Press, for example, recognized they as a singular pronoun in 2017. But before that, English grammar teachers the world over broke out their red pens to change it to he or she.
Yes, American grammar has a longstanding tradition of change — borrowing words from other languages and testing out different forms of expression — which could explain why many find it confusing. Although most people no longer call early education “grammar school,” it’s still an important topic of study. And as more people have access to updated information about the subject, it’s become easier to follow the rules.
Five authors on grammar
If anyone appreciates the role of grammar, it’s writers:
→”Ill-fitting grammar are like ill-fitting shoes. You can get used to it for a bit, but then one day your toes fall off and you can’t walk to the bathroom.” – novelist Jasper Fforde
→“The greater part of the world’s troubles are due to questions of grammar.” – philosopher Michel de Montaigne
→“And all dared to brave unknown terrors, to do mighty deeds, to boldly split infinitives that no man had split before — and thus was the Empire forged.” – novelist Douglas Adams
→“Grammar is a piano I play by ear. All I know about grammar is its power.” – American writer Joan Didion
Six examples of grammar rules
Here are six common grammar mistakes (and example sentences) to help you improve your writing:
Semicolon use: Semicolons are typically used to connect related ideas — but often a new sentence (instead of a semicolon) is more fitting.

Ending a sentence with a preposition: Some used to consider it wrong to end with a preposition (e.g. to, of, with, at, from), but now it’s acceptable in most informal contexts.

Splitting infinitives: Avoid it in formal settings, otherwise, it’s fine.

Beginning a sentence with because: It’s ok as long as the sentence is complete.

Subject-verb agreement: The verb of a sentence should match the subject’s plurality (or singularity).

Passive voice: In general, use active voice — that means the subject acts upon the verb. In passive voice, the verb acts upon the subject, resulting in a weaker sentence.
