American Sign Language in the context of "Tactile signing"

Sign languages (also known as signed languages) are languages that use the visual-manual modality to convey meaning, instead of spoken words. Sign languages are expressed through manual articulation in combination with non-manual markers. Sign languages are full-fledged natural languages with their own grammar and lexicon. Sign languages are not universal and are usually not mutually intelligible, although there are similarities among different sign languages.

Wherever communities of people with hearing challenges or people who experience deafness exist, sign languages have developed as useful means of communication and form the core of local deaf cultures. Although signing is used primarily by the deaf and hard of hearing, it is also used by hearing individuals, such as those with deaf family members including children of deaf adults.

Phonetics is a branch of linguistics that studies how humans produce and perceive sounds or, in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. The field of phonetics is traditionally divided into three sub-disciplines: articulatory phonetics, acoustic phonetics, and auditory phonetics. Traditionally, the minimal linguistic unit of phonetics is the phone—a speech sound in a language which differs from the phonological unit of phoneme; the phoneme is an abstract categorization of phones and it is also defined as the smallest unit that discerns meaning between sounds in any given language.

Phonetics deals with two aspects of human speech: production (the ways humans make sounds) and perception (the way speech is understood). The communicative modality of a language describes the method by which a language produces and perceives languages. Languages with oral-aural modalities such as English produce speech orally and perceive speech aurally (using the ears). Sign languages, such as Australian Sign Language (Auslan) and American Sign Language (ASL), have a manual-visual modality, producing speech manually (using the hands) and perceiving speech visually. ASL and some other sign languages have in addition a manual-manual dialect for use in tactile signing by deafblind speakers where signs are produced with the hands and perceived with the hands as well.

Deaf culture is the set of social beliefs, behaviors, art, literary traditions, history, values, and shared institutions of communities that are influenced by deafness and which use sign languages as the main means of communication. When used as a cultural label, especially within the culture, the word deaf is often written with a capital D and referred to as "big D Deaf" in speech and sign. When used as a label for the audiological condition, it is written with a lower case d. Carl G. Croneberg was among the first to discuss analogies between Deaf and hearing cultures in his appendices C and D of the 1965 Dictionary of American Sign Language.

The languages of Bolivia include Spanish and several dozen indigenous languages, most prominently Aymara, Quechua, Chiquitano, Guaraní and the Bolivian Sign Language (closely related to the American Sign Language). Indigenous languages and Spanish are official languages of the state according to the 2009 Constitution. The constitution says that all indigenous languages are official, listing 36 specific indigenous languages, of which some are extinct. Spanish and Quechua are spoken primarily in the Andes region, Aymara is mainly spoken in the Altiplano around Lake Titicaca, Chiquitano is spoken in the central part of Santa Cruz department, and Guarani is spoken in the southeast on the border with Paraguay and Argentina.

New Zealand Sign Language or NZSL (Māori: te reo Rotarota o Aotearoa; also known as te reo Turi o Aotearoa, literally "Deaf language of New Zealand") is the main language of the deaf community in New Zealand. It became an official language of New Zealand in April 2006 under the New Zealand Sign Language Act 2006. The purpose of the act was to create rights and obligations in the use of NZSL throughout the legal system and to ensure that the Deaf community had the same access to government information and services as everybody else. According to the 2013 Census, over 20,000 New Zealanders know NZSL.

New Zealand Sign Language has its roots in British Sign Language (BSL), and may be technically considered a dialect of British, Australian and New Zealand Sign Language (BANZSL). There are 62.5% similarities found in British Sign Language and NZSL, compared with 33% of NZSL signs found in American Sign Language.