About encoder and decoder.

An encoder is a device which transforms the data into some bits known only to it and the decoder is a device which transforms those coded bits to generate the original data again. These two are mainly used in computer technology but the underlying concept can be used anywhere. For example, the name ‘Delhi’ can be coded as ‘ihleD’ or ‘45#1278’. Later, the decoder regenerates the original ‘Delhi’ from this code as it knows the coding scheme.