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jee main is an entrance test which held every year across the country, jee main is conducts by NTA. the eligibility criteria to appear in jee main is candidates must complete or appearing in 12th class with physics, chemistry and mathematics is a mandatory subjects. based on jee main score top engineering institute of india like IIITS nits, government engineering colleges, VIT admission to b.tech courses is done. jee main exam can be attempted three consecutive times starting from the year of 12th pass.  based on jee main cutoff score you would be eligible to appear in jee advance which is the entrance test for iits, to join b.tech course. so jee main rank is widely accepted to study engineering in different institute in India. thus this exam is complementary for engineering aspirant. you may follow the below article to know about books compulsory to prepare for jee main exam:

https://engineering.careers360.com/articles/best-books-for-jee-main

Benefits of Jee Mains is that you get to test yourself among your peers throughout the country. You get to test yourself among lakhs of people and judge where you stand. In addition, Jee Mains exam results are widely accepted across colleges in India so it will also help you get admission.