As I'm going through the Feistel network in the DES algorithm.
While encryption uses a Feistel Network, the input block is divided into two halves left ($L$) and right half ($R$). In each round, the right half $R$ goes through unchanged. But the left part $L$ goes through an operation $F$.
I didn't understand why right halves is kept unchanged in a Feistel Network. Can anyone explain?