- Register is the variety of language chosen for a specific context — formal, semi-formal, or informal.
- Formal English avoids contractions, slang, and phrasal verbs; it uses precise Latinate vocabulary and passive constructions.
- Informal English is natural, personal, and conversational — it uses contractions, idioms, and everyday vocabulary.
- The same idea can be expressed at any register; the skill is matching your language to the audience and context.
- Most professional communication in English today sits in the “semi-formal” middle ground — polite but not stiff.
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What Is Register in English?
Register refers to the variety of language we use in a particular social situation. When you write a job application, you choose a formal register. When you text a friend, you use an informal one. Native speakers switch registers unconsciously many times a day. For learners, understanding these differences is essential for communication that sounds appropriate and natural in every context.
Linguists typically identify three broad registers: formal, semi-formal, and informal (sometimes further divided into colloquial and slang). This article focuses on the contrast between formal and informal English, with a section on the semi-formal register that dominates modern professional life. To practise noticing register in context, try our Grammar Quiz, which includes register-based questions.
Features of Formal English
Formal English is used in academic writing, official correspondence, business reports, legal documents, and formal speeches. It is characterised by the following features:
No contractions
Formal writing spells out all verb forms in full. Instead of it's, write it is. Instead of don't, write do not. Instead of we've, write we have. This applies equally to negative contractions (cannot rather than can't).
Precise, Latinate vocabulary
Formal English often prefers longer words of Latin or French origin over their shorter Germanic equivalents. Examples: commence (not start), endeavour (not try), utilise (not use), terminate (not end), inform (not tell). This does not mean formal English is always better — clarity should come first.
Passive voice
Formal writing uses the passive voice to create distance and objectivity. Mistakes were identified sounds more formal than We identified mistakes. Academic and scientific writing relies heavily on passive constructions to keep focus on results rather than researchers.
Complex sentence structures
Formal prose uses subordinate clauses, relative clauses, and nominalisations (turning verbs into nouns: the investigation of rather than investigating). Sentences tend to be longer and more syntactically dense than in informal speech or writing.
Impersonal tone
Formal English avoids the first person singular (I) where possible, preferring one, it is argued that, the evidence suggests, or passive constructions. This projects objectivity and neutrality.
Features of Informal English
Informal English is the language of everyday conversation, text messages, personal emails, social media, and casual writing. It is natural, warm, and often more efficient than formal alternatives. Its main features include:
Contractions and short forms
Contractions are the clearest marker of informal language: I'm, we're, you've, they'd, can't, won't, isn't, shouldn't. In spoken informal English, even further reductions occur: gonna (going to), wanna (want to), dunno (don't know).
Colloquial vocabulary and slang
Informal English uses everyday words and phrases: cool, loads of, stuff, get, hang out, freaked out, a bit. Slang is an even more restricted informal variety associated with particular groups or generations. Slang changes rapidly and can sound dated or inappropriate if used in the wrong context.
Phrasal verbs
Informal English is rich in phrasal verbs: put off, look into, get on with, bring up, figure out. Formal writing typically replaces these with single-word Latinate equivalents: postpone, investigate, continue, raise, determine.
Direct address and personal pronouns
Informal writing uses you and I freely and addresses the reader directly. Rhetorical questions, exclamations, and sentence fragments are all normal in informal prose.
Vocabulary: Formal vs Informal Pairs
The clearest way to see the formal/informal contrast is to compare equivalent vocabulary pairs. Test yourself on these with our Word Match exercise.
| Informal | Formal | Example (formal) |
|---|---|---|
| start / begin | commence | The ceremony will commence at noon. |
| end / finish | terminate / conclude | The contract terminates on 31 December. |
| get / obtain | acquire / receive | The company acquired three new clients. |
| ask | enquire / request | We would like to enquire about pricing. |
| tell / say | inform / state | We regret to inform you that... |
| use | utilise | Participants were asked to utilise the system. |
| need | require | Further information may be required. |
| help | assist / facilitate | Staff are available to assist delegates. |
| show | demonstrate / indicate | The results demonstrate a clear trend. |
| think / believe | consider / maintain | It is maintained that the policy is effective. |
| try | endeavour / attempt | We shall endeavour to respond promptly. |
| make sure | ensure | Please ensure all fields are completed. |
Grammar Differences
Beyond vocabulary, formal and informal English differ in important grammatical ways. These are tested in IELTS Academic and Cambridge B2/C1 examinations, and they matter in any professional English context. Use our Sentence Scramble to practise restructuring informal sentences into formal ones.
Formal grammar
- Full verb forms: do not, it is, we have
- Passive constructions: it was found that
- Nominalisations: the investigation of
- Subordinate and complex sentences
- Hedging: it appears that, evidence suggests
- No fragments or tag questions
Informal grammar
- Contractions: don't, it's, we've
- Active voice preferred: we found that
- Verb phrases: look into, find out about
- Short sentences and fragments
- Direct statements and exclamations
- Question tags: You're coming, right?
Note on Hedging
Hedging language — phrases like it could be argued that, evidence suggests, this may indicate — is a hallmark of academic writing. It signals intellectual caution and awareness of limitations. Avoid hedging in informal or conversational English, where it sounds evasive.
The Semi-Formal Middle Ground
Most real-world professional communication in English today is semi-formal. A business email to a client, a letter of inquiry, or a LinkedIn message does not need the stilted formality of a Victorian legal document — but it does need to be polite, clear, and professional. Semi-formal English:
- Uses some contractions (especially we're, I've, you'll) but avoids casual ones like gonna or wanna.
- Addresses the reader directly with you.
- Chooses clear vocabulary over overly Latinate options (start rather than commence).
- Uses active voice for clarity but switches to passive when appropriate.
- Avoids slang, idioms, and most phrasal verbs.
Think of semi-formal English as formal English with the stiffness taken out. It is polite, professional, and human. This register is also what IELTS General Training Writing Task 1 usually calls for. For vocabulary that bridges the gap, see our IELTS Vocabulary Guide.
Formal and Informal Emails: Side-by-Side Comparison
The email format is one of the most useful contexts for seeing formal/informal differences in action.
| Feature | Formal email | Informal email |
|---|---|---|
| Greeting | Dear Mr Smith / Dear Sir or Madam | Hi Tom / Hey! |
| Opening | I am writing with regard to your inquiry of 5 June. | Just wanted to check in about that thing we discussed. |
| Request | Could you please provide further clarification? | Can you explain a bit more? |
| Apology | I sincerely apologise for any inconvenience caused. | Sorry about that! |
| Closing | I look forward to your response at your earliest convenience. | Let me know what you think! |
| Sign-off | Yours sincerely / Yours faithfully | Cheers / Best / See you! |
Common Register Mistakes to Avoid
These are the errors that appear most often in formal and informal writing by learners at B1 to C1 level. Our Fill-in-the-Blank exercise gives targeted practice on many of these patterns.
- Using slang in academic writing: Expressions like loads of, tons of, or a bit are out of place in an essay. Use a great deal of, considerably, or somewhat instead.
- Using contractions in formal letters: Write do not, not don't, in formal correspondence.
- Phrasal verbs in formal writing: Replace look into with investigate, put off with postpone, find out with discover or determine.
- Being too formal in casual emails: Writing I trust this finds you well to a close colleague can sound cold or ironic. Match your register to the relationship.
- Mixing registers inconsistently: Switching between formal and informal language within the same piece of writing is confusing. Choose a consistent register and maintain it throughout.
For more on vocabulary choices, see our article on English False Friends, which covers common word-level errors that affect formality as well as meaning.
Practise Formal vs Informal English
Use LexFizz's interactive exercises to sharpen your register awareness and writing accuracy.
Start Practising Now →Frequently Asked Questions
Formal English uses complete sentences, precise vocabulary, no contractions, and passive constructions. Informal English uses contractions, slang, shorter sentences, and a conversational tone. The right register depends on your audience and context.
Use formal English in professional emails, academic essays, job applications, official letters, business reports, and presentations. Any context where you need to show respect or professionalism calls for a formal register.
Informal English includes contractions (it's, don't, we're), colloquial words (cool, loads, get), phrasal verbs (put off, get on with), sentence fragments (No worries!), and question tags (You're coming, right?).
Generally no. Formal writing avoids contractions. Instead of “it's” write “it is”; instead of “don't” write “do not”. This rule applies to academic writing, official correspondence, and formal reports.
Register refers to the variety of language used for a particular purpose or in a particular context. English has several registers including formal, semi-formal, informal, and colloquial. Switching register appropriately is a key communication skill.
Formal English tends to use Latinate or longer words (commence, utilise, enquire), while informal English prefers shorter Germanic equivalents (start, use, ask). Formal writing avoids slang, idioms, and phrasal verbs when single-word equivalents exist.
Not at all. Informal English is the natural choice for conversations with friends, casual texts, and social media. Using formal language in informal situations can sound unnatural or distant. The skill is knowing which register fits the situation.
Passive voice distances the writer from the action and removes personal pronouns, creating objectivity. For example: “Mistakes were made” (formal passive) vs “I made mistakes” (informal active). Academic and scientific writing relies heavily on the passive.
Hedging language (it appears that, evidence suggests, it could be argued) softens claims and signals academic caution. It shows you are aware of limitations in your argument. Phrases like “it seems” or “this may indicate” are common in academic writing.
Try rewriting the same paragraph in both registers. Use LexFizz's error correction and sentence rewrite exercises to practise transforming informal sentences into formal ones and vice versa. Reading academic texts and fiction side by side also helps build awareness.