web 2.0 definitions

User-Generated Content is a term referring to any info found on a medium(s) that is produced by end users, or people just like you and me who surf medias and put their own input or knowledge publicly out there. 
Long Tail is a concept used mainly for business concentrating on selling mass numbers of items in small quantities.
Network as Platform are the network services for internet scale distributed computing that extends across the internet. 
Folksonomy is this collaboration of "folk" and "taxonomy" that can be found on the web and now its known as a "social tagging system" used to structure knowledge from many different people outside of the web.
Syndication is when web information is found and made available places outside the site it originally came from or in other mediums instead.
Mass Collaboration refers to situations where many people contribute to one project or idea and a single product is developed from the many different views.
Computer Supported Collaboration refers to studies and mass collaborations that support other relationships and group works. The research behind one's work supported by others research gives it more stability and reliability.

Social-Software are software systems that allow users to interact and share data (Ex: social networking sites like Facebook, Myspace, Twitter, etc).

Video-Sharing Sites are internet sites that enable users to post video information (Ex: YouTube).
Wikis refer to websites that allows users to create or edit linked webpages using simple text editor.

Blogs are a type of website that enables the user to maintain regular entries of thoughts and media.

Mashup is a web page or application that combines data or functionality from two or more external sources to create a new service.