The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny. Clearly visible encrypted messages - irrespective of what is unbreakable - arouse interest and can themselves be incriminating in countries where encryption is illegal. Thus, while cryptography is the practice of protecting the content of a message alone, steganography is concerned with hiding the fact that a secret message is being sent, as well as hiding the content of the message. Steganography includes concealment of information within computer files. In digital steganography, electronic communications may include steganographic encoding within a transport layer, such as a document file, an image file, a program or a protocol. Media files are ideal for steganography transmission because of its large size. For example, a sender can start with a harmless image file and adjust the colour of every 100th pixel to match a letter of the alphabet, a change so subtle that someone who does not specifically look for it will not notice it.