What happens when HTML is improperly written?

When HTML is improperly written, it typically does not execute as intended, but it also does not throw an error in the way that programming languages might. Browsers are designed to be user-friendly and robust; hence, when they encounter malformed HTML, they often attempt to render the page as best as they can, ignoring or correcting the errors where possible. As a result, while the page may not display properly or show unexpected layouts and functionality, the lack of execution is handled gracefully, without invoking explicit error messages. This behavior underlines the flexibility built into web browsers to maintain user experience despite coding discrepancies.