This presentation discusses encoders. It defines an encoder as a combinational circuit that performs the reverse operation of a decoder, with a maximum of 2n inputs and n outputs. The simplest encoder is a 2n-to-n binary encoder, where only one of the 2n inputs is 1 at a time. Encoders convert a 1-out-of-2n input code to a binary output code, while decoders do the opposite. An example of an 8-to-3 binary encoder is shown, along with its truth table and simplified logic implementation using OR gates.