IELTS -International English Language Testing system:
There are mainly 2 categories- General and academic
IELTS Academic-it is needed if you are planning to enter an English -speaking educational institution.
IELTS General-it is often required by the embassies if you are planning to migrate to an English speaking country.
IELTS UKVI -International candidates who wish to pursue study ,job, or migrate to the Uk.