DNS is the system that helps a browser find the server for a website's name. It is like a contacts list that turns a person's name into the phone number needed to call them.
When someone enters a website address, DNS looks up where that site can be reached. The browser can then ask that server for the page.
People usually do not need to manage DNS just to browse. If a website address was recently changed, the saved directions may take time to update everywhere, so the site might not appear in the same way right away.