The term Web 2.0 is associated with web applications that facilitate participatory information sharing, interoperability, user-centered design, and collaboration on the World Wide Web. A Web 2.0 site allows users to interact and collaborate with each other in a social media dialogue as creators (prosumers) of user-generated content in a virtual community, in contrast to websites where users (consumers) are limited to the passive viewing of content that was created for them. Examples of Web 2.0 include social networking sites, blogs, wikis, video sharing sites, hosted services, web applications, mashups and folksonomies.
A wiki is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor. Wikis are typically powered by wiki software and are often used to create collaborative works. Examples include community websites, corporate intranets, knowledge management systems, and note services. The software can also be used for personal note taking
A blog (a blend of the term web log) is a type of website or part of a website. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order.Blog can also be used as a verb, meaning to maintain or add content to a blog.
4. “# tag” (Hash Tags)
Hashtags are a community-driven convention for adding additional context and metadata to your tweets. They’re like tags on Flickr, only added inline to your post. You create a hashtag simply by prefixing a word with a hash symbol:#hashtag.
Twitter is simply a micro blogging service. Meaning that you can write short updates of 140 characters maximum called “tweets” and send them out to your followers or contacts. Retweet on the other hand means that When someone re-tweets you, they are giving you the highest compliment you can get on Twitter by sharing your post or what you said with their own followers or contacts.