[know] what [is] what
1
to have a clear understanding or knowledge of a situation or matter
The origin of the idiom "know what is what" is not well-documented, but it is part of a broader group of idiomatic expressions related to knowledge and understanding. The use of "what is what" in this context suggests a clear understanding of the true nature or essence of something. This phrase is used to emphasize that someone possesses a deep understanding of a particular subject, situation, or set of circumstances. It implies that the individual can distinguish between what is true or important and what is not, making informed decisions or judgments.
- As an experienced chef, he knows what is what in the kitchen and can create amazing dishes from scratch.
- She's been in the fashion industry for years and knows what is what when it comes to the latest trends.
- A good leader should know what is what in their organization to make effective decisions.
- Having worked in IT for decades, he knows what is what in computer programming and can solve any technical issue.
- In the world of finance, you have to know what is what to make wise investment choices.