Web 1.0 allowed users to freely share and upload content online. As user-generated content grew in popularity with Web 2.0, spam has expanded from email to now include unsolicited audio and video content that could soon appear on popular video sharing websites, following the model of spam expanding from email to various online platforms. Research from the University of California San Diego found that spammers had to send 350 million spam messages to generate only 28 sales of male enhancement products, demonstrating the inefficiency of spam tactics.