Social networks –
Virtual communities that allow people to build personal web pages and then connect with others to share content and communication. Some of these venues appeal to broad groups, (i.e. Facebook, MySpace), whereas others are built around particular niches and demographics (i.e. LinkedIn).

Forums –
Areas for online discussion, in which multiple users can create topics of interest and then comment on these topics. Forums came about before the term “social media” and are a powerful and popular element of online communities.

Blogs
Perhaps the best known form of social media, blogs (short for web logs) are websites that typically feature posts, by an individual or group, which readers can comment upon. Blogs may vary in nature but tend to be popular, as they often provide an unvarnished, insider perspective on a particular topic.

Microblogging
social networking combined with bite-sized blogging, where small amounts of content (‘updates’) are distributed online and through the mobile phone network. Twitter is the clear leader in this field.

Content communities
Sites that allow users to post and share particular kinds of content. Such communities exist around anything from videos and photos to stories and links. Some of these sites include voting functions that allow the community to determine the relevance of content. The most popular content communities tend to form around photos ( Flickr), bookmarked links
( del.icio.us) and videos ( YouTube).

Wikis
Wikis are community-generated documents and databases. Approved users can create content and augment the content of others in the interest of creating better resources. The best-known wiki is Wikipedia.com, the online encyclopedia which has over 2 million articles in the English edition alone.

Podcasts
Audio and video files that are available by subscription, through services like Apple iTunes.

Virtual Worlds
This represents one of the most novel areas on the web, in which users can engage in immersive worlds. Some of these spaces closely mimic real-world notions such as community and economics.