Press briefings on COVID-19 by governments around the world have brought sign language interpreters to centre stage. These occasional appearances highlighted the existing gaps in accessibility for people with impaired hearing and verbal abilities. Although many of the world's languages are spoken, some are produced by hands, face and body. Sign languages emerge naturally among deaf communities and use visual-kinaesthetic modalities. Unlike spoken languages, which are primarily perceived auditorily, sign languages are perceived visually.
Contrary to popular perception, sign language is not universal. World sign languages are as varied as spoken languages. Some of the most publicly visible sign languages of the world are American Sign Language (ASL), British Sign Language (BSL), Langue des Signes Française (LSF), Nederlandse Gebarentaal (NGT) and Chinese Sign Language (CSL). Though sign languages are often thought of as invented by hearing people and as inferior or insufficient to spoken languages, they are fully developed, rule-governed linguistic systems that have their own grammars which are not dependent on spoken languages and can express anything.