Estonian Sign Language (ESL, Estonian: Eesti viipekeel) is the national sign language of Estonia. In 1998 there were about 4,500 signers out of a deaf population of 2000 and a hearing-impaired population ten times that number. It is widespread in the cities of Tallinn and Pärnu among deaf ethnic Estonians; deaf Russian Estonians in Tallinn use Russian Sign Language, Russians outside Tallinn tend to use a Russian–Estonian Sign Language pidgin, or may be bilingual. In its formative stages, Estonian Sign Language was influenced by Russian and Finnish Sign Language; for example, the ESL sign for 'butterfly' developed from the Finnish sign for 'bird'. There are several dialects, the most archaic of which is the Pärnu variety.