Quality assurance is a habit of looking at a page as a visitor, not only as its author. A short repeatable check catches small problems that quietly reduce trust.
Review the page
Read the heading and first paragraph aloud. Check dates, names, prices, links, images, alt text, spelling, and the main call to action. Open the page on a phone and test at a larger text size.
Test the behavior
Click internal and external links, submit forms with valid and invalid data, confirm success messages, and check that the page has a useful title and description. If the page is important, ask someone else to complete its main task without instructions.
A strong website process builds these checks into the work.