A tagline is a short phrase that captures a company's brand essence, personality, and positioning, and distinguishes the company from its competitors. Deceptively simple, taglines are not arbitrary. They grow out of an intensive strategic and creative process.

Taglines have become shorthand for what a brand stands for and delivers. Originally used in advertising as the centerpiece of a global marketing campaign, taglines historically have had much shorter life spans than logos. The best taglines have a long life, and transcend marketplace and lifestyle changes. They are meaningful and memorable, and require frequent and consistent use.

Source: Designing Brand Identity - Alina Wheeler