"IDK" is an informal abbreviation that means "I don’t know." It shows that you do not have information or are not sure about something. It is part of texting or internet slang and is common in casual situations, like texting friends, group chats, social media comments, or quick online messages. Avoid using "IDK" in formal emails, school essays, exams, or when speaking politely to teachers, bosses, or clients; instead, write or say "I don’t know."
For example:
Mark: "Are you coming to the party tonight?"
Jennifer: "IDK yet, I’m still deciding."
