 In 2013, the United Kingdom "Advertising Standards Authority ("ASA) began to advise celebrities and sports stars to make it clear if they had been paid to tweet about a product or service by using the hashtag #spon or #ad within tweets containing endorsements.The practice of harnessing social media personalities to market or promote a product or service to their following is commonly referred to as Influencer Marketing.The Cambridge Dictionary defines an "influencer" as any person (personality, blogger, journalist, celebrity) who has the ability to affect the opinions, behaviors, or purchases of others through the use of social media.