Microdot is not a very familiar device, even though in this modern 21st century. Honestly, microdot is some kind of text or an image that substantially reduced in size onto a 1mm disc to prevent detection by unintended recipients.
The traditional microdots are usually circular around one millimeter in diameter. However, it can be made into many different shapes and sizes.
According to the history, a Parisian photographer named Dagron used a photographic shrinking technique to permit each pigeon to carry a high volume of messages. It’s known as the creation of the first Microdot.
After that, the actual microdot technique was used for steganographic purposes in Germany between World War I and World War II. Then, it was later used by many countries to pass messages through insecure postal channels.
Now, the microdot is evolved into a more advent level, where the sophisticated yet effectiveness digital microdot has been developed for the ease of the users.