The Duolingo English Test is a measure of English language proficiency. The test has been designed for maximum accessibility; it is delivered via the internet, without a testing center, and is available 24 hours a day, 365 days a year. It has been designed to be efficient. It takes less than one hour to complete the entire process of taking the test (i.e., onboarding, test administration, uploading). It is a computer-adaptive test (CAT), and it uses item types that provide maximal information about English language proficiency. It is designed to be user- friendly; the onboarding, user interface, and item formats are easy to interact with.