IELTS offers two main versions of the test:

1. Academic IELTS: This version is primarily for individuals applying to study at universities and other higher education institutions in English-speaking countries. It assesses a candidate’s ability to understand and use complex academic language.
2. General Training IELTS: This version is usually taken by individuals who plan to migrate to English-speaking countries or wish to pursue training programs, work experience, or secondary education in such countries. It focuses on practical and everyday language skills.

The IELTS test measures four key language skills:

1. Listening: Candidates listen to recordings of native English speakers and answer questions based on the information they hear.
2. Reading: Test takers read passages and answer questions to demonstrate their understanding of the text.
3. Writing: This section requires candidates to complete two writing tasks, which could be a report, essay, letter, or other types of written responses.
4. Speaking: A one-on-one interview with an IELTS examiner assesses the candidate’s spoken English abilities, including fluency, vocabulary, and pronunciation.

IELTS scores are reported on a nine-band scale, ranging from Band 1 (non-user) to Band 9 (expert user). The band score reflects the individual’s proficiency in English.

Given that this information is accurate up to September 2021, I recommend visiting the official IELTS website or relevant official sources for the most up-to-date and comprehensive details about IELTS. Policies, formats, and other details related to language tests might have changed since my last update.