What it means to be good at your software engineering job

I started working full time as a software engineer last year and unlike my days in college, I have got to read and write software on a daily basis for around the past 9 months. In this time, I realized that not everyone in a software engineering role knows everything about software and that the notion of being an expert was in some ways different than what I had in mind.

I learnt that knowing what something is and knowing where and what to look for to know what it is are different things. A beginner would assume that an expert in something would know every intricacy and would have the entire mental framework of how everything functions as they work. In reality, an expert knows that "understanding" works like a progressive JPEG - it only gets more and more clear as time passes. An actual expert would have a better mental image of what to look for, even if they are not pretty sure about how something works.