Social media are interactive computer-mediated technologies that facilitate the creation and sharing of information, ideas, career interests and other forms of expression via virtual communities and networks.[1] The variety of stand-alone and built-in social media services currently available introduces challenges of definition; however, there are some common features:[2]

Social media are interactive Web 2.0 Internet-based applications.[2][3]
User-generated content, such as text posts or comments, digital photos or videos, and data generated through all online interactions, is the lifeblood of social media.[2][3]
Users create service-specific profiles for the website or app that are designed and maintained by the social media organization.[2][4]
Social media facilitate the development of online social networks by connecting a user's profile with those of other individuals or groups.[2][4]
Users usually access social media services via web-based technologies on desktops and laptops, or download services that offer social media functionality to their mobile devices (e.g., smartphones and tablets). As users engage with these electronic services, they create highly interactive platforms through which individuals, communities, and organizations can share, co-create, discuss, and modify user-generated content or pre-made content posted online.

Networks formed through social media change the way groups of people interact and communicate. They "introduce substantial and pervasive changes to communication between organizations, communities, and individuals."[1] These changes are the focus of the emerging fields of technoself studies. Social media differ from paper-based media (e.g., magazines and newspapers) and traditional electronic media such as TV broadcasting in many ways, including quality,[5] reach, frequency, interactivity, usability, immediacy, and performance. Social media outlets operate in a dialogic transmission system (many sources to many receivers).[6] This is in contrast to traditional media which operates under a mono-logic transmission model (one source to many receivers), such as a newspaper which is delivered to many subscribers, or a radio station which broadcasts the same programs to an entire city. Some of the most popular social media websites, with over 100 million registered users, include Facebook (and its associated Facebook Messenger), YouTube, WeChat, Instagram, QQ, QZone, Weibo, Twitter, Tumblr, Telegram, Reddit, Baidu Tieba, LinkedIn, LINE, Snapchat, Pinterest, Viber, MeWe, and VK.

Observers have noted a range of positive and negative impacts of social media use. Social media can help to improve an individual's sense of connectedness with real or online communities, and can be an effective communication (or marketing) tool for corporations, entrepreneurs, non-profit organizations, advocacy groups, political parties, and governments.