The term 'online participation' is simply defined as the participation of online activities. This includes any form of online behaviour from visiting a website, watching a video or commenting on a post. Online participation is also informally referred to online communities, which consists of constant online interaction with other internet users 
Wikipedia is a free online encyclopedia ran by the Wikipedia Foundation. Those who can access the site can also contribute to the information it provides, thus defining it to be an online community.
Facebook is a free social networking site and is home of 1.39 billion active monthly users (as of February 2015). Online activity on Facebook includes liking, commenting, sharing, tagging, gaming, and much more. Facebook is considered the biggest social networking website, with 4.5 billion 'likes' happening daily.
Twitter is a social networking service that enables users to send and read short 140-characters messages called 'tweets'.  Registered users can post and read tweets, but unregistered users only have the ability to read them. Twitter can be accessed through the website interface, SMS or mobile devices. Twitter headquarters is based in San Francisco and has more than 25 offices around the world.
Twitter was first created in March 2006 by Jack Dorsey, Evan Williams, Biz Stone and Noah Glass and was launched in July 2006. As of 2014, Twitter has more than 500 millions users,with an average of 58 million tweets made per day.
Google+ is a social network owned and operated by Google Inc.
Google+ launched in June 2011 as a social network. Features included the ability to post photos and status updates to the stream or interest based communities, group different types of relationships into Circles, a multi-person instant messaging, text and video chat called Hangouts, events, location tagging, and the ability to edit and upload photos to private cloud-based albums.
Google executives subsequently described Google+ as "a social layer across all of Google's services", allowing them to share a user's identity and interests.
Approximately 540 million monthly active users make use of the social layer by interacting with Google+'s enhanced properties, like Gmail, +1 button, and YouTube comments. Some 300 million monthly active users participate in the social network, interacting with the Google+ social networking stream.
Instagram is an online mobile photo-sharing, video-sharing and social networking service that enables its users to take pictures and videos, and share them on a variety of social networking platforms, such as Facebook, Twitter, Tumblr and Flickr. A distinctive feature is that it confines photos to a square shape, in contrast to the 4:3 aspect ratio typically used by mobile device cameras. Users can also apply digital filters to their images. The maximum duration for Instagram videos is 15 seconds
Instagram was created by Kevin Systrom and Mike Krieger, and launched in October 2010. The service rapidly gained popularity, with over 100 million active users as of April 2012 and over 300 million as of December 2014.
Snapchat is a photo messaging application, that allows its users to take pictures, record videos, add drawings and text, and send them to other users, creating conversation. The sent videos and photographs are known as 'snaps'. Users have a set time limit, of no more than 10 seconds, for how long their snap can be viewed, and after will be deleted from snapchat servers. As of may 2014, app users were sending 700 million photos and videos a day, whilst stories were being viewed 500 million times per day.