Quizlet offers free online study tools starting with flashcards and other games, aimed at helping students learn material. Students can create their own study sets or can make use of the approximately 16 million flash card sets created by other students. In addition to "flashcards" the site also offers games.

How Does It Work? Quizlet helps students focus on the facts that they are learning by making lists (say, words and definitions), and then self-testing their knowledge of these facts by using online flashcards and games. Among the games included in Quizlet are

• Speller—Type what you hear in this audio-powered study mode.
• Learn—Track your correct/incorrect answers and retest the ones you've missed.
• Test—Randomly generate tests based on your flashcard set.
• Scatter—Race against the clock to drag and match terms/definitions.
  
• Space Race—Type in the answer as terms/definitions scroll across the screen.

Students can either create their own study sets or make use of the approximately 16 million flash card sets created by other students.

Quizlet has a "text-to-speech" function that lets students hear words spoken out loud in about 18 languages. It also uses "VoiceOver," a screen-reading technology from Apple that lets students hear what’s onscreen and control their keyboard without visuals -- making it possible for  vision-impaired students to use the Quizlet app.

There is a (free) iPhone app as of August 2012. As of late 2012, Android and iPad apps were in the works.

In November 2012, Quizlet was piloting a multiplayer game based around words. In essence, Quizlet floats an unusual word and the players (or students) have less than a minute to write a unique (and frequently funny) sentence that uses the word. Sentences are displayed in some common space (such as a white board) and all the students vote for their favorite definition. Quizlet has testing the game in more than 40 classrooms in the San Francisco area. Teachers who have been trying out Quizlet's multiplayer game say their students love the competitive nature--and they like the learning moments.

Who is using it? Students and teachers: As of November 2012, the product is used by about 12 million unique visitors a month who spend an average of eight to 10 minutes there. The site does not require registration although by registering, students can create and save their own study files.

Business model? Quizlet has been entirely bootstrapped by founder Andrew Sutherland and CEO Dave Margulius. It has no outside investors as of November 2012. It makes money through modest advertising and by selling premium accounts. A "premium" account to Quizlet PLUS, which costs $15 per year, allows students to save images from their computer to their study sets. (This is a helpful function for, say, medical students learning body parts.) Premium accounts are also ad-free. Company managers say it is supporting itself.

Competition: There are a number of other flashcard applications available through the iTunes store; few of those are as comprehensive as Quizlet. One learning aid competitor used by many teachers is Quia. Quia has a class-based subscription fee in contrast to the either free version of Quizlet (or the student-priced model).

(Here's an EdSurge story about Quizlet.)