2. Slideshare An online slide hosting service Users can upload files; Powerpoint PDF, Keynote
3. Twitter A microbloging service Send & read text-based posts of up to 140 charcters, called “tweet” 200 million users, over 200 million tweets per day Fail whale
4. Facebook SNS (social networking service) 750 million users Mark Zuckerberg (The Social network)
5. Lang-8 A language exchange SNS The company is based in Kyoto, Japan Select native language & target languages