There are specific eligibility criteria set by the AIEEE and IIT JEE that determine who can appear for these entrance exams. To be eligible for these exams, you must pass a qualifying examination of 12th standard or equivalent with specific subjects (typically Mathematics, Physics, and Chemistry) and secure the required minimum marks set by the respective examination authorities. The eligibility criteria differ slightly for AIEEE and IIT JEE, and they can change from time to time. Refer to the official websites and information brochures of the AIEEE and IIT JEE for the latest updates on eligibility criteria.