Learning by building turns abstract knowledge into repeated decisions about behavior, structure, tools, and tradeoffs. A working project creates immediate feedback when assumptions are incomplete or an implementation does not behave as expected.
The method is most useful when the project is small enough to finish and review. Copying generated output without understanding it produces less learning, so builders should inspect choices, test the result, and explain what changed.
ELI5
Learning by building means gaining skill by making something real instead of only reading about it. Each feature creates a practical question, and each mistake shows which idea or technique needs more attention.
For example, building a task tracker teaches more than the button layout. The builder encounters data storage, editing, sorting, empty states, and tests as the application starts to work.
