Cognitive Load is what matters
Readable version | Chinese translation | Korean translation | Turkish translation
It is a living document, last update: August 2025. Your contributions are welcome!
Introduction
There are so many buzzwords and best practices out there, but most of them have failed. We need something more fundamental, something that can't be wrong.
Sometimes we feel confusion going through the code. Confusion costs time and money. Confusion is caused by high cognitive load. It's not some fancy abstract concept, but rather a fundamental human constraint. It's not imagined, it's there and we can feel it.
Since we spend far more time reading and understanding code than writing it, we should constantly ask ourselves whether we are embedding excessive cognitive load into our code.
Cognitive load
Cognitive load is how much a developer needs to think in order to complete a task.
When reading code, you put things like values of variables, control flow logic and call sequences into your head. The average person can hold roughly four such chunks in working memory. Once the cognitive load reaches this threshold, it becomes much harder to understand things.
... continue reading