What is JEE Mains all about and what is the mode of exam?

JEE MAINS joint entrance examination is  an exam conducted by cbse (central board of secondary education) to regulate admission in NITS and IIITS, and many other central govt and state govt colleges and universites.The candidate who qualify this exam will becomes applicable for jee advance where you get the chance to get a seat in prestigious iits.jee mains exam consists of 90 mcq questions each question has weightag of 4 marks and -1 for wrong ans there would be 3 sections maths, chemistry and physics and the mode of examination was both online and offline but from next year it would be online only and their is a good news that they will give you 2 chances to give the exam means exam will be occur twice the year