If you plan to study in higher education or seek professional registration, you can take an IELTS Academic test. Or if you want to study in secondary education, work or migrate to an English-speaking country, IELTS General Training test might be right for you.
Where you want to study, work or migrate to will affect which test you need to take.
Make sure you check with the relevant government or institution you are applying to, to confirm which test you need to take and what score they ask for, as government agencies, institutions and other recognising organisations set their own IELTS entry requirements.