Twin

Twins are two offspring produced by the same pregnancy. Twins can either be monozygotic ("identical"), meaning that they can develop from just one zygote that will then split and form two embryos, or dizygotic ("fraternal"), meaning that they can develop from two different eggs; each are fertilized by separate sperm cells.

In contrast, a fetus which develops alone in the womb is called a singleton, and the general term for one offspring of a multiple birth is multiple.

Statistics

The twin birth rate in the United States rose 76% from 1980 through 2009, from 18.9 to 33.3 per 1,000 births. The Yoruba have the highest rate of twinning in the world, at 45–50 twin sets (or 90–100 twins) per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovaries to release an egg from each side.

In Central Africa there are 18–30 twin sets (or 36–60 twins) per 1,000 live births. In Latin America, South Asia, and Southeast Asia, the lowest rates are found; only 6 to 9 twin sets per 1,000 live births. North America and Europe have intermediate rates of 9 to 16 twin sets per 1,000 live births.

Instagram

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 either publicly or privately on the app, as well as through a variety of other social networking platforms, such as Facebook, Twitter, Tumblr, and Flickr. Originally, a distinctive feature was that it confined photos to a square shape, similar to Kodak Instamatic and Polaroid images, in contrast to the 4:3 aspect ratio typically used by mobile device cameras. In August 2015, version 7.5 was released, allowing users to post photos captured in any aspect ratio. 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 as a free mobile app. The service rapidly gained popularity, with over 100 million active users as of April 2012 and over 300 million as of December 2014. Instagram is distributed through the Apple App Store, Google Play, and Windows Phone Store. Support for the app is available for iPhone, iPad, iPod Touch, and Android handsets, while third-party Instagram apps are available for BlackBerry 10 and Nokia-Symbian Devices.

Twitter

Twitter (/ˈtwɪtər/) is an online social networking service that enables users to send and read short 140-character messages called "tweets".

Registered users can read and post tweets, but those who are unregistered can only read them. Users access Twitter through the website interface, SMS or mobile device app. Twitter Inc. is based in San Francisco and has more than 25 offices around the world.

Twitter was created in March 2006 by Jack Dorsey, Evan Williams, Biz Stone, and Noah Glass and launched in July 2006. The service rapidly gained worldwide popularity, with more than 100 million users posting 340 million tweets a day in 2012. The service also handled 1.6 billion search queries per day. In 2013, Twitter was one of the ten most-visited websites and has been described as "the SMS of the Internet". As of May 2015, Twitter has more than 500 million users, out of which more than 332 million are active.

History

Creation and initial reaction

Twitter's origins lie in a "daylong brainstorming session" held by board members of the podcasting company Odeo. Jack Dorsey, then an undergraduate student at New York University, introduced the idea of an individual using an SMS service to communicate with a small group. The original project code name for the service was twttr, an idea that Williams later ascribed to Noah Glass, inspired by Flickr and the five-character length of American SMS short codes. The decision was also partly due to the fact that domain twitter.com was already in use, and it was six months after the launch of twttr that the crew purchased the domain and changed the name of the service to Twitter. The developers initially considered "10958" as a short code, but later changed it to "40404" for "ease of use and memorability". Work on the project started on March 21, 2006, when Dorsey published the first Twitter message at 9:50 PM Pacific Standard Time (PST): "just setting up my twttr". Dorsey has explained the origin of the "Twitter" title: