Twitter is an American microblogging and social networking service on which users post and interact with messages known as "tweets". Registered users can post, like, and retweet tweets, however, unregistered users have the ability to only read tweets that are publicly available. Users interact with Twitter through browser or mobile frontend software, or programmatically via its APIs. Prior to April 2020, services were accessible via SMS. The service is provided by Twitter, Inc., a corporation based in San Francisco, California, and has more than 25 offices around the world. Tweets were originally restricted to 140 characters, but the limit was doubled to 280 for non-CJK languages in November 2017. Audio and video tweets remain limited to 140 seconds for most accounts.

Twitter was created by Jack Dorsey, Noah Glass, Biz Stone, and Evan Williams in March 2006 and launched in July of that year. By 2012, more than 100 million users posted 340 million tweets a day, and the service handled an average of 1.6 billion search queries per day. In 2013, it was one of the ten most-visited websites and has been described as "the SMS of the Internet". By the start of 2019, Twitter had more than 330 million monthly active users. In practice, the vast majority of tweets are written by a minority of users.On April 25, 2022, the Twitter board of directors agreed to a $44 billion buyout by Elon Musk, the CEO of SpaceX and Tesla, potentially making it one of the biggest deals to turn a company private.

Social media are interactive technologies and digital channels that facilitate the creation and sharing of information, ideas, interests, and other forms of expression through virtual communities and networks. While challenges to the definition of social media arise due to the variety of stand-alone and built-in social media services currently available, there are some common features:

Social media are interactive Web 2.0 Internet-based applications.

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.

Users create service-specific profiles for the website or app that are designed and maintained by the social media organization.

Social media helps the development of online social networks by connecting a user's profile with those of other individuals or groups.Users usually access social media services through web-based apps on desktops 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 which individuals, communities, and organizations can share, co-create, discuss, participate, and modify user-generated or self-curated content posted online. Additionally, social media are used to document memories; learn about and explore things; advertise oneself; and form friendships along with the growth of ideas from the creation of blogs, podcasts, videos, and gaming sites. This changing relationship between humans and technology is the focus of the emerging field of technological self-studies. Some of the most popular social media websites, with more than 100 million registered users, include Facebook (and its associated Facebook Messenger), TikTok, WeChat, Instagram, QZone, Weibo, Twitter, Tumblr, Baidu Tieba, and LinkedIn. Depending on interpretation, other popular platforms that are sometimes

referred to as social media services include YouTube, QQ, Quora, Telegram, WhatsApp, Signal, LINE, Snapchat, Pinterest, Viber, Reddit, Discord, VK, Microsoft Teams, and more. Wikis are examples of collaborative content creation.

Many social media outlets differ from traditional media (e.g., print magazines and newspapers, TV, and radio broadcasting) in many ways, including quality, reach, frequency, usability, relevancy, and permanence. Additionally, social media outlets operate in a dialogic transmission system, i.e., many sources to many receivers, while traditional media outlets operate under a monologic transmission model (i.e., one source to many receivers). For instance, a newspaper is delivered to many subscribers and a radio station broadcasts the same programs to an entire city.Since the dramatic expansion of the Internet, digital media or digital rhetoric can be used to represent or identify a culture. Studying how the rhetoric that exists in the digital environment has become a crucial new process for many scholars.

Observers have noted a wide range of positive and negative impacts when it comes to the use of social media. 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. Observers have also seen that there has been a rise in social movements using social media as a tool for communicating and organizing in times of political unrest.