Step 1 : Introduction to the question "Which invention was named after a medieval king?"
...The name "Bluetooth," which refers to the standard for shortrange wireless connections, is derived from Viking King Harald Gormsson, who is credited with uniting Scandinavia. Like many medieval rulers, he also had a nickname: blátonn in Old Norse. It translates to Bluetooth. Scholars believe that his nickname originated from a distinctive dead tooth that appeared blue. The now iconic Bluetooth logo is actually a combination of King Harald's initials, written in Scandinavian. Intel mobile engineer Jim Kardac came up with the name in 1997 after reading a book about Vikings.