Browser testing exercises the rendered interface, navigation and interactions of a web application. It can reveal integration problems that unit tests or source inspection do not show.
A useful browser test completes the main user flow and checks important states such as loading, errors, empty inputs, mobile layouts and persisted data after refresh.
ELI5
Browser testing means opening the website and trying it the way a visitor would. The tester clicks, types and checks what appears on the screen.
For example, a tester can create a note, refresh the page and confirm that the note is still present and readable on both a laptop and phone-sized screen.
