[Graphic of the lormhand icluding the touchpoints for the letters.
By using their tactile – kinesthetic sense (= through Movement and Touch) blind and deafblind people can train to exchange information with their partners of communication with the help of tactile signs. One efficient way to do that is the Lorm-Method*, which is at least very helpfull for people who used to be sighted in their earlier days and who are therefore able to decode written language somehow.
* The Lorm-Alphabet was developed by Hieronymus Lorm in 1881.
More info: taubblindenwerk