Twitter is an online news and social networking service where users post and interact with messages, "tweets," restricted to 140 characters.

Registered users can post tweets, but those who are unregistered can only read them.

Users access Twitter through its website interface, SMS or a mobile device app.

Twitter Inc. is based in San Francisco, California, United States, and has more than 25 offices around the world.

Instagram is a mobile photo-sharing application and service that allows users to share pictures and videos either publicly or privately on the service, as well as through a variety of other social networking platforms, such as Facebook, Twitter, Tumblr, and Flickr.

Originally, a distinctive feature was its confining of photos to a square, similar to Kodak Instamatic and Polaroid SX-70 images, in contrast to the 4:3 aspect ratio typically used by mobile-device cameras.

In August 2015, version 7.5 was released for mobile devices, allowing users to upload media captured in any aspect ratio, but not at full size.

Users can also apply various digital filters to their images.

In June 2013, Instagram added support for videos, allowing prerecorded square standard definition resolution clips of up to 15 seconds to be shared; later updates introduced support for widescreen resolutions at 360p and longer recording times for either pre-recorded (up to one minute per video, or up to 10 minutes with a multi-video post) or disappearing live videos (up to one hour).

Facebook is an American for-profit corporation and online social media and social networking service based in Menlo Park, California.

The Facebook website was launched on February 4, 2004, by Mark Zuckerberg, along with fellow Harvard College students and roommates, Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes.

A hashtag is a type of label or metadata tag used on social network and microblogging services which makes it easier for users to find messages with a specific theme or content.

Users create and use hashtags by placing the hash character (also known as the number sign or pound sign) in front of a word or unspaced phrase, either in the main text of a message or at the end.

Searching for that hashtag will yield each message that has been tagged with it.

A hashtag archive is consequently collected into a single stream under the same hashtag.

For example, on the photo-sharing service Instagram, the hashtag #bluesky allows users to find all the posts that have been tagged using that hashtag.

Social Media Analytics as a part of social analytics is the process of gathering data from stakeholder conversations on digital media and processing into structured insights leading to more information-driven business decisions and increased customer centrality for brands and businesses.