Study Tips All Levels LexFizz Team 10 min read
Part of the English Register Series

Related guides: Business English Phrases, Conjunctions Guide, and Academic Vocabulary exercises.

Key Takeaways
  • Register is the level of formality you choose based on your audience, relationship, and context.
  • Formal English uses longer words (often Latin/French origin), avoids contractions, and uses complex grammar.
  • Informal English uses shorter words, contractions, idioms, and simpler sentence structures.
  • Choosing the wrong register — too formal with friends, too casual in a job application — can create a bad impression.
  • The same idea can be expressed at any register; the words and grammar change, not the meaning.

Want to practise formal and informal vocabulary? Try Flash Cards →

Every time you write or speak in English, you make a choice about register — how formal or informal your language is. Native speakers adjust their register automatically depending on who they are talking to and why. For English learners, this can be one of the most subtle but most important aspects of the language to master. Getting the register wrong — using slang in a university essay, or writing a job application as if texting a friend — can undermine even grammatically perfect English.

What Is Register?

Register refers to the variety of language used in a particular social situation. Linguists typically describe a spectrum from very formal (legal documents, academic writing, official speeches) through neutral/standard (most news writing, professional emails) to informal (casual conversation, text messages, social media) and very informal/slang (close friends, dialect).

The choice of register depends on three main factors:

  • Audience: Who are you speaking to? (boss, friend, unknown official)
  • Purpose: What are you trying to achieve? (persuade, socialise, inform)
  • Medium: How are you communicating? (essay, email, text, speech)
Key insight: Register is not about being "correct" or "incorrect". Both formal and informal English are correct — in the right context. The mistake is mismatching register to situation.

Vocabulary Differences

The most visible difference between formal and informal English is vocabulary. Formal English tends to use words with Latin or French roots (longer, more abstract), while informal English prefers shorter, simpler words with Anglo-Saxon origins.

Informal / NeutralFormal / Academic
askenquire / request
getobtain / acquire / receive
buypurchase
useutilise / employ
find outascertain / determine
startcommence / initiate
end / finishconclude / terminate
helpassist / facilitate
tellinform / notify
showdemonstrate / illustrate
thinkconsider / contend / argue
a lot ofa considerable number of / substantial
aboutregarding / concerning / with regard to
needrequire / necessitate
Pro tip: Formal vocabulary is not always better. In everyday writing like emails to colleagues, using "utilise" where "use" will do can make you sound pompous rather than professional. Match your word choices to the situation.

Grammar Differences

Formal and informal English also differ in their grammar patterns. The key differences are in contractions, sentence structure, passives, and questions.

Contractions

Formal English avoids contractions; informal English uses them freely.

Formal

"I am writing to inform you that the meeting has been rescheduled."

Informal

"I'm writing to let you know the meeting's been moved."

Passive Voice

Formal writing frequently uses the passive voice to create an impersonal tone; informal language uses the active voice more naturally.

Formal

"The proposal was reviewed by the committee and subsequently approved."

Informal

"The committee looked at the proposal and approved it."

Question Forms

Formal English uses indirect questions; informal English uses direct questions.

Formal

"I was wondering if you could let me know when the report will be ready."

Informal

"Do you know when the report will be ready?"

Sentence Structure

Formal writing tends to use longer, more complex sentences with subordinate clauses. Informal writing uses shorter sentences and coordinating conjunctions (and, but, so).

Formal

"Despite the initial challenges encountered during the implementation phase, the project was completed within the agreed timeframe and budget."

Informal

"There were some problems at first, but we got it done on time and on budget."

When to Use Each Register

Knowing when to use each register is as important as knowing how. The table below gives practical guidance.

ContextAppropriate RegisterKey features
University essay / academic paperFormalNo contractions, impersonal tone, hedging language, passive voice
Job application or CV covering letterFormalFull sentences, Latin vocabulary, polite and direct
Email to a new clientFormal – Semi-formal"Dear Mr Smith," "Kind regards," no contractions
Email to a colleague you know wellSemi-formal – Informal"Hi Sarah," contractions acceptable, shorter sentences
Text message to a friendInformalContractions, abbreviations, short sentences, emoji acceptable
Speech or presentation to colleaguesSemi-formalSpoken grammar, contractions, but no slang
IELTS Task 2 essayFormalNo contractions, hedging, impersonal or formal first person
Social media post (professional)Semi-formalConversational but professional, some contractions acceptable

Register in Practice: Emails and Essays

The most common contexts where English learners need to consciously manage register are formal emails and academic essays. Below are side-by-side comparisons of the same message in different registers.

Requesting Information: Formal vs Informal Email

Formal Email

Dear Ms Chen,

I am writing to enquire about the availability of the Advanced English course commencing in September. Could you please provide details regarding the course fees and enrolment procedure?

Yours sincerely,
A. Kowalski

Informal Email

Hi Li,

Just wanted to check if there are still places left on the September English course. What's the cost and how do I sign up?

Thanks,
Anna

Expressing an Opinion: Essay vs Conversation

Academic Essay

"It could be argued that increased access to technology has, in many respects, enhanced educational outcomes, particularly in developing nations where traditional infrastructure has historically been limited."

Casual Conversation

"I think technology's been really good for education, especially in countries that don't have great schools."

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Frequently Asked Questions

What is register in English language?
Register refers to the variety or level of formality in language, chosen according to the social context, the relationship between speaker and listener, and the purpose of the communication. English has a spectrum from very formal (academic writing, legal documents) through standard/neutral to informal (casual conversation, text messages). Choosing an appropriate register is a key aspect of communicative competence in any language.
What are the main differences between formal and informal English?
The main differences are in vocabulary, grammar, and tone. Formal English uses longer Latin-derived words (enquire, obtain, commence), avoids contractions, uses the passive voice, and constructs complex sentences. Informal English prefers shorter Anglo-Saxon words (ask, get, start), uses contractions freely, prefers active voice, and uses simpler, shorter sentences. Informal English also includes idioms, slang, and colloquialisms that would be inappropriate in formal contexts.
Why is it important to use the correct register?
Using the wrong register creates a poor impression regardless of how grammatically accurate your English is. Being too informal in a job application or academic essay signals a lack of professional awareness. Being too formal with friends or colleagues can make you seem cold, distant, or difficult to work with. In IELTS and other English exams, using an inappropriate register is directly penalised in the marking criteria for Lexical Resource and Coherence.
Can I use contractions in formal English?
No — contractions (I'm, don't, it's, we're) are characteristic of informal and semi-formal English and should be avoided in formal writing such as academic essays, business letters, job applications, and official documents. Always write the full form: "I am", "do not", "it is", "we are". In spoken formal English, contractions are slightly more acceptable but full forms are still preferred in very formal speeches or presentations.
What is the difference between formal and semi-formal English?
Semi-formal English is the middle ground between formal and casual. It is professional and polite but accessible and not stiff. Examples of semi-formal contexts include emails to established colleagues, most workplace communications, and professional social media posts. Semi-formal English may use contractions occasionally, uses first names, tends toward active voice, and avoids both slang and overly complex vocabulary. It is the most commonly required register in professional life.
How do I know which register to use in an email?
Ask three questions: Who am I writing to? (Do I know them? Are they senior to me?) What is the purpose? (Making a request, sharing information, complaining?) What is the context? (First contact vs ongoing relationship, professional vs personal). Use formal for first contact, senior executives, complaints, or legal and financial matters. Use semi-formal for regular professional correspondence. Use informal only for close colleagues in an established relationship. When in doubt, choose one level more formal than you think is necessary.
Is it wrong to use informal English?
Absolutely not — informal English is entirely correct and appropriate in the right contexts. Casual conversation, messages to friends, informal blog posts, and social media all call for informal language. The error is not using informal English; it is using it in situations that call for formal language. Equally, using unnecessarily formal language in casual settings can sound unnatural, off-putting, or even comical to native speakers.
How does formal English differ in speaking vs writing?
Spoken formal English is generally somewhat less formal than written formal English, because speech is more immediate and interactive. Even in formal speeches or presentations, contractions appear occasionally and sentences are shorter than in written documents. Written formal English tends to be more structured, avoids repetition, uses more complex grammar, and requires precise punctuation. In both modes, formal language avoids slang, colloquialisms, and overly casual vocabulary.
What are some common informal phrases and their formal equivalents?
Some common pairs: "I think" → "It could be argued that / It is my contention that"; "a lot of" → "a considerable number of / substantial"; "find out" → "ascertain / determine"; "get in touch" → "contact / communicate"; "help" → "assist / facilitate"; "sorry" → "I apologise"; "thanks" → "I am grateful for / Thank you for your kind assistance"; "buy" → "purchase"; "end" → "conclude / terminate".
How can I improve my ability to switch between registers?
The best approach is to read widely across different text types — academic articles, business emails, news stories, novels, and informal blogs — and pay attention to how the vocabulary and grammar shift. Try rewriting the same paragraph in different registers as an exercise. Also practise writing different types of emails (formal complaint, informal thank-you, semi-formal request) and compare them. Exposure to authentic English in diverse contexts is the most reliable way to internalise register awareness.