A message used in conjunction with the Masterbrand or a sub-brand. For instance, the strapline for General Electric would be "GE, Bringing Good Things to Life.".
A strapline is an advertising slogan used as a secondary sentence attached to a brand name. Its purpose is to emphasise a phrase that the company wishes to be remembered by, particularly for marketing a specific corporate image or connection to a product or consumer base. The usage "strapline" rather than "advertising slogan" is chiefly British.