Social network

• Profiles that represent people.
• Connections between them — friendships or follows, which together form the social graph.
• A stream of content from those connections, whether an algorithmic feed, a chronological one, or both.
• Interaction: reactions, comments, shares, and usually private messaging.

A forum without profiles or connections is a discussion board. A video site where you never interact with other viewers is a media platform. The more a service is organized around people and their links to each other, the more it is a social network.

The terms overlap, and people use them interchangeably. The useful distinction: social media is the broad category of platforms for publishing and consuming user-made content, often to strangers. A social network emphasizes relationships — who you know and talk to. A video app where most views come from people who don't follow the creator is social media first; an app where you mostly see and message people you've connected with is a social network first. Many products are both.

The phrase is older than the apps. Sociologists used “social network” for the web of ties between people in a village, a school or a workplace. Online services borrowed it because they make those ties visible and searchable.