IELTS is an acronym which stands for International English Language Testing System IELTS and basically, the IELTS is an English proficiency exam to test your knowledge of English how well you can read write speak and understand English. 

People take up the IELTS exam usually for the following reasons: 

If you're planning to study abroad  you're planning to move to another country or for some other purpose the IELTS is generally taken by students who are planning to study in a university or college in an English-speaking environment or to move to countries like Canada or Australia where IELTS is the English proficiency exam which is accepted for official purposes by them the IELTS is also requested at times when people have already immigrated to countries such as

Canada or Australia to certify their English language ability in terms of their profession. 

There are basically two types of IELTS exams:

there's the general exam and the academic exam.

The academic exam is for students who want to pursue their education in an English speaking university. 

The general IELTS is usually taken for those people who are planning to emigrate to English speaking countries such as USA, Australia, UK etc. 

The IELTS exam is subdivided into 4 different parts:

LIstening

Reading

Writing and 

Speaking

You will be given a score band ranging from 1-9 for each section. The average of all these scores would be your band score. 

IELTS test scores range from 1-9 where 1 means a non-user and 9 means an expert. There is also a 0 score which means not attempted. 

According to the British Council, score 9 implies that you are an expert in English. As you come down, the value of the counts also diminishes. For example, rating 8 would indicate very good and score four would mean limited/average. 

In the case of reading and listening, the scoring is quite straightforward. For example, if you get 30 questions correct out of 40, then for a General exam the band score will be six, and for an Academic exam, the band score jumps to a 7. 

The writing section is slightly different to grade. 

The scores are calculated using a  detailed rubric. The important keys the examiner looks for is coherence and cohesion, Lexical Resource, Grammatical range, Task achievement and task response.