KFC has been an extensive advertiser since the establishment of the first franchise in 1952. The chain is well known for the "finger-lickin' good" slogan, which originated in 1956. The phrase was adopted nationally by the company by the 1960s and went on to become one of the best-known slogans of the twentieth century. The trademark expired in the U.S. in 2006 and was replaced in that market with "Follow your taste" until 2010. In 2011, the "finger lickin' good" slogan was dropped in favor of "So good," to be rolled out worldwide. In 2015, along with a revamp of their U.S. advertising, KFC returned to using "Finger Lickin' Good." As of April 2016, KFC began using the slogan "Colonel Quality, Guaranteed."

Source: Wikipedia