Adeste Fideles, also known as 'O Come All Ye Faithful, ' is a traditional Christmas carol that has been sung for centuries. The Latin phrase 'Adeste Fideles' translates to 'Come All Ye Faithful' and is the title of the carol. The carol was originally written in Latin by John Francis Wade in the 18th century, but has since been translated into many languages. The carol is often sung during the Christmas season and is a popular choice for Christmas concerts and services.