abbr tag for Abbreviations
The abbreviation tag allows you to pass on useful information about an abbreviation without spelling it out on the page.
For example, I might use the abbreviation LLC in a story about a business. Some people might not know what "LLC" means, but I can tell them without interrupting the flow of the story for those who do know the meaning.
Rest your cursor on this abbreviation: LLC
The appearance of the abbreviation can depend on the browser being used, but all major browsers support the abbreviation tag.
You have to add a title attribute to the abbreviation tag in order for the tool tip explaining what the abbreviation means to show up. That's coded like this:
title="Explain your abbreviation here">LLC