Usually you need to take IELTS if you are applying for a job/studies in a collage or university in English speaking country or if you are migrating to such country. There are 2 type of IELTS test. Academic and General. Academic is for future students and General is for immigrants.
The IELTS Routine
The IELTS test consists of four parts in the following order
Listening test takes about 30 minutes - 20 minutes to listen to a tape and to answer questions on what you hear , and 10 minutes to transfer your answer to Answer sheet.
Reading test takes 1 hour and your task is to read passage of text and answer questions according to what you have read.
Writing test takes also 1 hour and is divided into 2 sub-parts: 20 minutes to write a letter/report and 40 minutes to write an essay.Speaking test takes up to 15 minutes and consists of 3 parts : Personal Interview, Little Speech and a Discussion.
All the parts continue one after another, and only before the Speaking test you get a break.