A tagline is a short, memorable phrase paired with a brand — often alongside the logo — that captures a key part of its positioning or personality in a handful of words.
Effective taglines are specific enough to say something real about the brand, rather than generic enough to apply to any competitor. A tagline that could sit under any business in the category isn't doing its job, no matter how catchy it sounds.
Not every business needs one — a tagline should clarify or sharpen positioning, not exist simply because competitors have one. A forced tagline is often worse than no tagline at all.