Disability definitions and classification establish obligations for accessibility, reasonable accommodation and inclusive education under the Act. The Act defines core concepts-such as person with disability, person with benchmark disability, reasonable accommodation and universal design-and specifies roles for certifying authorities, competent authorities and appropriate Governments. The Schedule classifies specified disabilities (physical, visual, hearing, intellectual, mental illness, chronic neurological conditions, blood disorders, multiple disabilities and notified categories) with operative criteria to guide certification, eligibility and institutional duties for accessibility, inclusive education, employment facilitation and rehabilitation.