Hey

IIT Bombay is one of the best IIT's in the country. You may get admission here in B.Tech after 12th.The Institute conducts educational programmes leading to the degree of Bachelor of Technology (B. Tech.).

For this you have to appear for JEE Mains and Advance both. You may  appear for JEE Advance only if you qualify Mains so it is the first step towards getting into IITB. Your top ranking in Jee Advance may help you get through the IIT Bombay and admissions to IITs will be based only on category-wise All India Rank (AIR) in JEE ADVANCED.

Hope this helps!!