A young woman shrugging.
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One fantastic thing about the internet community is how rapidly it pushes the boundaries of language. Twitter-born words, phrases, and #hashtags emerge constantly in response to news and social media. IDK is one of the more popular online abbreviations used in informal communication and memes.

“I Don’t Know”

IDK is an abbreviation of the phrase “I don’t know,” and it be can spelled capitalized or uncapitalized. According to Grammarly, the abbreviation has been around since sometime around 2002 (or even earlier), when it appeared in text speak. On Urban Dictionary, the phrase is defined as the shorthand form for “I don’t know” in a comment posted in 2003.

The abbreviation is most commonly used and understood by younger generations (think generations Y and Z), but don’t bet that someone who isn’t as tech- or text-savvy will understand what the phrase means.

According to Google Trends, IDK is most often used in the United States, Poland, and Moldova. The usage of the term really began to skyrocket on the web in 2007. The abbreviation’s popularity rose again with another significant hike during the current global pandemic with a focus in memes, possibly reflecting people’s confusion and uncertainty over the state of society during the lock-down period.

RELATED: What Is a Meme (and How Did They Originate)?

How to Use IDK

IDK should be used as shorthand for “I don’t know” in text and instant messaging to express uncertainty when trying to come up with an answer to a question, or when trying to describe something unknown.

Here are a few proper ways to use IDK in text:

  • IDK what that means.
  • IDK about that.
  • I should pick up bread, but idk if the store is open now.

If you’re feeling extra confident, saying IDK aloud to a group of friends will invite a lot of laughs and self-inflicted embarrassment (just don’t do it in public unless you have no shame.)

It’s meaning and semantics have remained the same, but a few variations have appeared over time.

“IDEK” and Other Variations

A speech bubble with a question mark inside it.
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There are a few variations of IDK that are common in messaging platforms. All of these variations can be spelled capitalized or uncapitalized. IDK can be used to respond quickly to messages, but online slang should be avoided in many professional settings.

A common variation is “IDEK” or “I don’t even know.” For example, “IDEK who that is.”

You can use the “IDW,” or “I don’t want,” shorthand to show you don’t want something or when you don’t want to do something. For example, “IDW to go to the park.”

Use “IDTS,” or “I don’t think so,” to express subtle doubt and uncertainty. For example, if you’re not sure whether or not the keys are in the house, respond with “IDTS.”

“IDC,” or “I don’t care,” should not be confused with IDK, however, you can use them in the same sentence.

For example:

  • Person 1: “Who was that?”
  • Person 2: “idk and idc”

The opposite of IDK is IK (I know), which is another popular online abbreviation that is used most commonly in text messaging. Alternatively, you can use “IKR” which translates to “I know, right?” and is usually applied in ironic contexts.


There’s a ton of online slang that IDEK, and if you’re curious about other internet abbreviations and acronyms, check out our pieces on GG and IRL.

Joshalynne Finch Joshalynne Finch
Joshalynne is a freelance writer and lifelong learner who always loves studying new things. She enjoys checking out the latest grammar books and writing about video games more than anything else.
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