Blogs (short for Web logs) are online journals or diaries hosted on a Web site and often distributed to other sites or readers using RSS (see below).
Collective intelligence refers to any system that attempts to tap the expertise of a group rather than an individual to make decisions. Technologies that contribute to collective intelligence include collaborative publishing and common databases for sharing knowledge.
Mash-ups are aggregations of content from different online sources to create a new service. An example would be a program that pulls apartment listings from one site and displays them on a Google map to show where the apartments are located.
Peer-to-peer networking (sometimes called P2P) is a technique for efficiently sharing files (music, videos, or text) either over the Internet or within a closed set of users. Unlike the traditional method of storing a file on one machine—which can become a bottleneck if many people try to access it at once—P2P distributes files across many machines, often those of the users themselves. Some systems retrieve files by gathering and assembling pieces of them from many machines.
Podcasts are audio or video recordings—a multimedia form of a blog or other content. They are often distributed through an aggregator, such as iTunes.
RSS (Really Simple Syndication) allows people to subscribe to online distributions of news, blogs, podcasts, or other information.
Social networking refers to systems that allow members of a specific site to learn about other members’ skills, talents, knowledge, or preferences. Commercial examples include Facebook and LinkedIn. Some companies use these systems internally to help identify experts.
Web services are software systems that make it easier for different systems to communicate with one another automatically in order to pass information or conduct transactions. For example, a retailer and supplier might use Web services to communicate over the Internet and automatically update each other’s inventory systems.
Wikis, such as Wikipedia, are systems for collaborative publishing. They allow many authors to contribute to an online document or discussion.