5. Define an online social network and differentiate between Facebook, Twitter, and LinkedIn

An online social network is a platform where individuals can connect and interact with each other virtually. These platforms allow users to share ideas, activities, events, and interests within their individual networks.

1. Facebook: Facebook is a general social networking site that allows users to connect with friends and family. Users can post text, photos, and multimedia which is shared with their network of friends. Facebook also allows users to join groups, share events, and a multitude of other activities.

2. Twitter: Twitter is a 'microblogging' service that allows users to send and read short 140-character messages called 'tweets'. Users can follow other users' tweets and interact with them using retweets and likes. Twitter is often used for news sharing and real-time discussions.

3. LinkedIn: LinkedIn is a professional networking site. It is primarily used for professional networking, including employers posting jobs and job seekers posting their CVs. LinkedIn allows users to create profiles and "connections" to each other in an online social network which may represent real-world professional relationships.