Advertising

However, as any user of social media knows, hashtags have now spilled out into Facebook, Snapchat, Instagram and advertising materials worldwide.

Perhaps the most powerful advertising words in history come from the poetic pen of Chairman Mao: "Until you reach the Great Wall, you're no hero.".

Sometimes people who offer these free services use advertising to make money.

Sprite picked up popularity with teenagers in the 1980's after several advertising campaigns targeted at teenagers.

In the 1990's, Sprite launched the 'Jooky' ad campaign, which poked fun at other soft drinks and their lack of authenticity and bandwagon-driven style of advertising, foremost among the competitive soft drinks mocked was Pepsi.