CBC (Cipher Block Chaining) is a block cipher mode that allows encryption of each plaintext block using the previous ciphertext block. Each block is XORed with the previous ciphertext block before encryption to prevent the same plaintext blocks from encrypting to the same ciphertext. A 1-bit error in transmission affects two blocks by garbling the current block and flipping a bit in the next. To prevent issues with errors in the initialization vector, it should be encrypted or derived from a known value. CBC encryption is parallelizable for decryption but not encryption.