New messages notification
For many years, the new messages notification appeared like this:
It was colloquially referred to as the "orange bar of death" or "orange bar of doom" (OBOD).
For logged-in users, the Echo extension replaces the original bar with the Echo bubble and a smaller notification bar (which temporarily replaces the link to the editor's User talk page):
To see what the original (and still current for logged-out users) new messages notification looks like by default in various skins, use the links below. (The design in the version shown at the top, is from MonoBook/Vector):
Preview with available skins: