The International English Language Testing System (IELTS) is one of the most widely recognized English language proficiency tests in the world.  It is an international standardized test of English language proficiency for non-native English language speakers.

It is jointly managed by the British Council, IDP and Cambridge English, and was established in 1989.

IELTS assesses the language ability of candidates who need to study or work in environments where English is the primary language of communication.

The test measures four key language skills:

1. Listening: Candidates listen to recordings of native English speakers and answer questions based on what they hear.
2. Reading: Candidates read passages from various sources and answer comprehension questions to demonstrate their understanding of the written material.
3. Writing: Candidates are required to complete two writing tasks. The first task usually involves describing or explaining visual information, while the second task requires writing an essay expressing an opinion or argument.
4. Speaking: Candidates participate in a face-to-face interview with an examiner, where they engage in a conversation, discuss a particular topic, and express their thoughts and opinions.

IELTS scores are reported on a scale from 1 to 9 for each of the four skills, as well as an overall band score, which is an average of the four individual scores. Different institutions and organizations may have specific score requirements for admission or employment purposes, so candidates typically take the IELTS test to meet these requirements.