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An unforgettable phrase that perfectly encapsulates a brand promise is the basis of many a successful campaign. Once found, a slogan can define a brand for decades. Here are the top 10 slogans for the 20th Century, as well as another five that Ad Age just couldn't leave out.

1. "A diamond is forever" - DeBeers
2. "Just do it" - Nike
3. "The pause that refreshes" - Coca-Cola
4. "Tastes great, less filling" - Miller Lite
5. "We try harder" - Avis
6. "Good to the last drop" - Maxwell House
7. "Breakfast of champions" - Wheaties
8. "Does she ... or doesn't she?" - Clairol
9. "When it rains, it pours" - Morton Salt
10. "Where's the beef?" - Wendy's

Honorable mentions

• "Look Ma, no cavities!" - Crest toothpaste
• "Let your fingers do the walking" - Yellow Pages
• "Loose lips sink ships" - public service
• "M&Ms melt in your mouth, not in your hand" - M&M candies
• "We bring good things to life" - General Electric