The concept of sigma additivity is important in measure theory.

South African Sign Language is the official sign language of South Africa.

Chilean Sign Language is the official sign language used in Chile.

Adamorobe Sign Language is an indigenous sign language used in Adamorobe.

Honduras Sign Language is the primary means of communication for the Deaf community in Honduras.

Argentine Sign Language is the primary language used by the Deaf community in Argentina.

Brazilian Sign Language is the official sign language used in Brazil.

Hausa Sign Language is a unique form of communication used by the Deaf community in Nigeria.

Bolivian Sign Language is the primary means of communication for the deaf community in Bolivia.

Algerian Sign Language is the primary language used by the Deaf community in Algeria.