在密码学中，明文是指传送方想要接收方获得的可读信息。 明文经过加密所产生的信息被称为密文，而密文经过解密而还原得来的信息被称为明文。

In cryptography, plaintext is information a sender wishes to transmit to a receiver. Cleartext is often used as a synonym. Plaintext has reference to the operation of cryptographic algorithms, usually encryption algorithms, and is the input upon which they operate. Cleartext, by contrast, refers to data that is transmitted or stored unencrypted (that is, 'in the clear').