In the strict geographic sense, the Indian subcontinent is divided politically among three countries: India, Pakistan, and Bangladesh. It is the part of Asia south of the Himalayas that juts into the Indian Ocean between the Arabian Sea and the Bay of Bengal.
In broader everyday use, the term often also covers Nepal, Bhutan, Sri Lanka, and the Maldives, which overlaps with the political region called South Asia. Afghanistan is sometimes counted in South Asia but is not considered part of the subcontinent.
Source: Indian subcontinent, Wikipedia