A microdot is text or an image substantially reduced in size onto a small disc to prevent detection by unintended recipients. Microdots are normally circular and around one millimetre in diameter but can be made into different shapes and sizes and made from various materials such as polyester or metal. The name comes from the fact that the microdots have often been about the size and shape of a typographical dot, such as a period or the tittle of a lowercase i or j. Microdots are, fundamentally, a steganographic approach to message protection.