Ceremonies for graduating students date from the first universities in Europe in the twelfth century. At that time, Latin was the language of scholars. A universitas was a guild of masters (such as MAs) with license to teach. "Degree" and "graduate" come from gradus, meaning "step". The first step was admission to a bachelor's degree. The second step was the masters step, giving the graduate admission to the universitas and license to teach. Typical dress for graduation is gown and hood, or hats adapted from the daily dress of university staff in the Middle Ages, which was in turn based on the attire worn by medieval clergy.

The tradition of wearing graduation hats in Sweden has been in place since the mid-eighteenth century. The cap is typically a white sailor hat with a black or dark blue band around it, a crown motif, and a black peak at the front. The graduation hat tradition was initially adopted by students at Uppsala University. The headgear then became popular across several other European nations as well.

https://en.wikipedia.org/wiki/Graduation