Quizlet

Quizlet is a multi-national American company which creates and designs tools used for studying and learning. Founded by Andrew Sutherland in October 2005 and released to the public in January 2007, Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes (similar to Kahoot!). As of April 2021, Quizlet's website claims it has over 350 million user-generated flashcard sets, 3 billion total study sessions, and more than 50 million active users. 
History.
Quizlet was founded in 2005 by Andrew Sutherland as a studying tool to aid in memorization for his French class, which he "aced". Quizlet's blog, written mostly by Andrew in the earlier days of the company, claimed it reached 50,000 registered users in 252 days online.
On April 15, 2008, Quizlet made its first national TV appearance when Sutherland was featured on the Mike and Juliet Show. Two years later, Quizlet receives its 1,000,000th registered user. 
Until 2011, Quizlet shared staff and financial resources with the Collectors Weekly web site. In 2015, Quizlet announced raising $12 million from Union Square Ventures, Costanoa Venture Capital, Altos Ventures and Owl Ventures to expand its digital study tools and grow internationally.
In 2011, Quizlet added the ability to listen to content using text-to-speech. In August 2012, it released an app for the iPhone and iPad and shortly afterward one for Android devices.
Quizlet launched a redesign in August of 2016 and hired Matt Glotzbach as CEO a few months earlier in May. Also in 2016, Quizlet launched "Quizlet Live", a real-time online matching game where teams compete to answer all 12 questions correctly without an incorrect answer along the way.
Glotzbach announced in 2018 that Quizlet would be opening offices in Denver, Colorado in 2018, citing how Quizlet has, "a big vision at Quizlet to provide the most intelligent study tools in the world, and our expansion into Denver, a city with incredible tech ingenuity, will help us more quickly build the next generation of learning tools used by students everywhere".
During the COVID-19 pandemic, Glotzbach announced he was opening Quizlet's premium service, Quizlet Teacher, for free to all users who have an account registered as a teacher. 
Study modes and games.
As a memorization tool, Quizlet lets registered users create sets of terms and definitions customized for their own needs. These sets of terms can then be accessible to students by studying a variety of modes.
Controversy.
Students on Quizlet will often upload information that can be used to cheat within the classroom.<ref>