Which community primarily uses Indian Sign Language (ISL)?

The primary community of users of Indian Sign Language (ISL) is the Deaf community in India—that is, people who are Deaf (with little or no functional hearing) who use sign language as their main mode of communication. In addition to Deaf users, ISL is also used by hard-of-hearing people, interpreters, teachers working with Deaf learners, family members of Deaf persons, and others in their social circle who use it to communicate with the Deaf person. 

ISL is a visual-manual language (hand shapes, movements, facial expressions, and body posture) rather than a spoken one. It has its own grammar and syntax distinct from Indian spoken languages. 

The fact that ISL is the “primary” language of many Deaf persons in India means it is the main mode of everyday communication, social interaction, education, and community bond for them. It is not just an auxiliary tool; for many it is the first and full language.