When you learn English vocabulary, you might hear the terms formal language and informal language. To be honest, in daily life it is not a huge problem to mix these up, but for IELTS it is important that you show an understanding of the difference between them.

In this lesson, I want to tell you about informal language. I’ll explain what it is, give plenty of examples, and then say when you should and should not use it.

What is informal language?

When most people learn a language, they tend to focus on learning vocabulary. Indeed, this is a great way to make early progress. However, at a later point you need to think about how appropriate your language is to certain situations.

Thus, people sometimes break vocabulary into two types: formal and informal language. Sometimes, you will see another category, which is semi-formal.

This is not really the best way of thinking of vocabulary because arguably most words do not fall simply into these categories. Think about common words:

  • table
  • coffee
  • camera
  • backpack
  • road

These are neither formal nor informal. They are just words.

However, we do have a lot of words that can be classed as informal. These tend to include contractions, slang, and idioms.

Informal language is generally the sort of language we use when speaking with friends or writing in a very informal context, such as a social media post. In the old days, most newspapers were very formal but now it’s quite common to see informal language in certain news articles and even government publications. This is probably because the editors of those publications want their words to be widely understood and informal language is much easier to understand than formal language.

You can read about the difference between formal and informal language here.


Let’s start with contractions, which are generally seen as informal.

A contraction is when two or more words come together to form a single word. In the previous sentence, I said “let’s.” This is short for “let us.” We frequently use an apostrophe in this sort of contraction. Here are some more examples:

ContractionFull Meaning
He’sHe is or he has
I’mI am
Let’sLet us
She’dShe had or she would
This’llThis will
We’llWe will
You’dYou had or you would
You’reYou are

Note that there were several examples where a word could have two possible meanings. You will have to figure out which one is correct from the context.

  • I’d been waiting for an hour. (I’d = I had)
  • I’d be careful if I were you. (I’d = I would)

The above examples are not exactly the most informal words. They’re very common in daily life and you’ll frequently find them in writing that is not wholly formal. I suppose you could call these “slightly informal” and a lot of people might even just consider them “normal language.”

Some contractions, however, are more informal:

ContractionFull Meaning
CouldaCould have
GimmeGive me
GonnaGoing to
OughtaOught to
ShouldaShould have
WannaWant to
WouldaWould have

These are a bit more informal than the previous ones. Typically, they would be seen as very informal language.

a list of contractions for english learners

Other abbreviated words include:

Short FormFull Form
AbsAbdominal muscles

These can be quite regionally specific. When I was a school pupil, we often abbreviated our classes but these terms might not be understandable to people from other countries. For example, we said “soc ed” instead of “social education” or “home ec” instead of “home economics.” Some would be more widely used, such as “physical education” becoming “PE.” My English friends say “caff” instead of “café” and my Australian friends say “aggro” instead of “aggressive.” However, I would personally not use these because I’m from Scotland and they sound strange to me.

common contractions


The above were words that have been shortened but we also have acronyms, which are abbreviations formed by using the first letter of each word in a phrase. Common ones include:

AcronymFull Meaning
ATMAutomated teller machine
GIFGraphic interchange format
LOLLaugh(ing) out loud
OMGOh my god
TBHTo be honest

Certain commonly used acronyms, particularly ones referring to companies and organisations, could definitely be used in formal language. For example, academic essays make frequent use of these. However, you would need to write the full form first and then the shortened form later. Words like this include NASA, the USA, the BBC, and so on.

Other acronyms stem from the internet. People use these terms to get their meaning across quickly. These are typically considered very informal.


I suppose we could include abbreviated terms as slang but I’d like to keep them separate for now and treat slang a bit differently. Likewise, “slang” could also be defined as pretty much any informal language.

Here, however, I’ll classify it as very informal words and phrases that are usually specific to a demographic group (ie young people or people from a specific place). In the modern era, however, it seems that slang is becoming more widespread because of the internet.

Whilst certain shortened words are definitely slang (such as “legit,” which I mentioned above), other terms are more distinct.

A classic example is the word “cool,” meaning hip or trendy. This is actually quite old slang and as such it has largely been incorporated into regular English. You could say “He saw a cool café and stopped in for a coffee.” I don’t think anyone would consider this very informal now. It’s just normal English.

There is no point in me teaching you the slang that I grew up with because, as a child of the 1990s, most of my slang knowledge is out of date! As such, I’ll mention some slang that I know is more common among young people today:

Slang TermMeaning in Regular English
DeadTo have found something very, very funny
FlexTo brag or show off
GhostTo leave without saying anything (particularly to leave a date or to not call them back later)
Low-keyTo a small extent
On fleekWell executed
SaltyTo feel bitter about something
WokeThe extremist part of the liberal half of the political spectrum

Note: As I am now 37 years old and living outside of my native country, I’m probably not the best authority on slang! I suggest you check out these resources:

You can also let me know any terms you use in the comment section.


An idiom is a group of words whose meaning is not necessarily possible to determine from its component parts. For example, the idiom “over the moon” means to be very happy, but this is quite strange to English learners because people don’t literally go over the moon when they have fun!

Idioms are a very interesting part of language to study but they are not really that helpful in daily life and certainly not for IELTS students or anyone interested in academic English. That’s because they are quite informal and have really limited use. Even when used slightly out of context, they can be baffling.

I really don’t value idioms much (you can read why here) but I understand why people want to learn them.

Here is a short list of some common idioms:

Cool as a cucumberCalm and unfazed by stressful situations
Face the musicExperience the consequences of your actions
In hot waterTo be in trouble
Keep your chin upStay positive
Lose your touchTo stop being good at something
Ring a bellTo feel that something is familiar or hints at a forgotten memory
Twist (someone’s) armConvince someone to do something

Note: If you see someone online promising that “These idioms will make you sound like a fluent speaker!” then you should ignore them. They are lying to you. Idioms can be mildly useful, but they won’t help you very much.

Here’s a useful tip: If you just learn English normally (ignoring most idioms), then you can always ask someone what they mean when they use one in conversation. It might lead to an interesting discussion.

Informal language and IELTS

It is really useful to learn informal language because you will encounter it quite often. Particularly nowadays, with the internet reaching into almost everyone’s life, you will see contractions and slang popping up all over the place.

However, can you use informal language in IELTS?

Well, it depends.

Certainly, you can and should use informal language in the speaking test. I would caution against going too informal and I’d suggest avoiding “bad language” (such as swearing), but you can definitely use most informal terms in this part of the test. For example:

  • Do you often go to the cinema?
  • Yeah, sure. Actually, I’m gonna go to the cinema with some friends on Friday. We’re hoping to catch a new horror flick.

In this example, each of the following is fairly informal:

  • Yeah
  • Sure
  • Actually
  • I’m
  • Gonna
  • We’re
  • Catch
  • Flick

That’s eight informal words in just three sentences!

As for the writing test, it depends on whether you’re doing the general or academic IELTS exam. In the general test, you might be asked to write an informal letter. In this case, you should definitely throw in a few informal words and phrases. However, a formal letter would require formal language and an essay always requires formal language. Thus, you should never put slang or contractions into your task 2 essays. Likewise, a task 1 academic report should also be written in formal language, with no slang or contractions.

new ielts book
My book about IELTS letters has guidance on formal and informal language.

Given that you just have to fill in gaps or choose the correct option, the issue of formal vs informal language is not really an issue for the reading or listening tests, but you certainly could encounter both types of English. In the listening test, you’ll certainly hear people talk in everyday (ie informal) English, so you should be prepared for that.


Informal language is very common and so every English learner should devote some time to learning it. When it comes to IELTS, you’ll probably use more formal language… but you should learn both types and try to understand the differences.

Also be aware that “informal language” contains a variety of forms and you could even view it as such:

  • Very informal
  • Quite informal
  • Slightly informal

Indeed, the whole formal vs informal language issue could be viewed on a spectrum:

spectrum of formality in language

Keep in mind that you should always use words as accurately as possible. That means knowing their precise meaning, their common collocations, and their level of formality.