Many color laser printers add tiny yellow dots to each page they print. These dots encode the printer serial number and additional information. A recently published research paper reveals new information about this secret code.

In the intro of the German TV film “Im Namens meines Sohnes” a message is hidden. It is easy to solve.

US artist Andy Bauch hid messages in his Lego artworks. Blog reader Christian Baumann has now solved two of the codes.

The gravestone of William and Elizebeth Friedman in Washington, DC, bears a hidden message. A few days ago I had the chance to go on site and take a look at it. Here’s my report, including a video that shows Elonka Dunin explaining the code.

William and Elizebeth Friedman, two of history’s greatest codebreakers, published a book dubunking the idea of hidden codes in the works of Shakespeare. However, the book itself contains a code. Can you find it?

In July 1918 a British officer, who was imprisoned in Turkey, sent a letter to a girl in London. This letter contains a hidden message. Can somebody help me to find out what kind of code was used?

Blog reader Martin Lohner has created a piece of music that hides a message. Can you find it?

Fascinating stories about hidden messages in texts, pictures and other objects – this is what my new book “Versteckte Botschaften” is about. Here are some of the highlights of this work.

Daniel Kammen, energy advisor of US president Donald Trump, has hidden an acrostic in his letter of resignation. He’s not the first one to do so.

My blog post about acrostics (especially about one in a letter of resignation from a presidential advisory committee) has been quite popular among my readers. Here are a few more acrostics.