Cyril and Methodius were two brothers who lived a very long time ago, around 1,100 years ago in a place called Thessaloniki. They became very smart and learned many things, including how to speak and read many different languages.
One day, a king who ruled over a place called the Great Moravia asked Cyril and Methodius to help him teach his people about God. The problem was that the people spoke a language that was very different from the languages Cyril and Methodius knew. They knew it would be very difficult to teach the people about God in a language they didn't understand.
So, Cyril and Methodius decided to make a new alphabet, which is a set of letters that can be used to write down words. This new alphabet was called the Glagolitic alphabet, and it was designed to help the people of Great Moravia read and write in their own language.
Once they had created the new alphabet, Cyril and Methodius began to teach the people about God using their new language. They translated many important religious texts into the new language, so that the people could understand them better. They even wrote a book called the Slavic Bible, which was the first Bible to be written in a Slavic language.
Cyril and Methodius became very famous for their work in Great Moravia. People started calling them saints, which means they were very holy people who did good things. They were also declared to be the co-patrons of Europe, which means that they are considered to be very important people in the history of Europe.
Today, Cyril and Methodius are remembered for their great work of creating a new alphabet and teaching people about God in their own language. They are celebrated on a special holiday called the Feast of Saints Cyril and Methodius, which is celebrated on February 14th every year.