In business, a slogan or tagline is "a catchphrase or small group of words that are combined in a special way to identify a product or company," according to Entrepreneur.com's small business encyclopedia.
In many ways, they're like mini mission statements.
Companies have slogans for the same reason they have logos: advertising. While logos are visual representations of a brand, slogans are audible representations of a brand. Both formats grab consumers' attention more readily than the name a company or product might. Plus, they're simpler to understand and remember.
The goal? To leave a key brand message in consumers' minds so that, if they remember nothing else from an advertisement, they'll remember the slogan.