When I was learning Spanish, I read about a celebration called "Three Kings Day". I just brushed it off as the Spanish celebration for Christmas and never thought about it again. I was in middle school and high school, education wasn't as important to me back then, and like most kids I just wanted to pass the test.
Many years later when I was teaching kids Spanish in homeschooling, education of course was way more important to me. We studied this a bit deeper to find out what Three Kings Day was, and in the process learned more about other terms that are interwoven throughout what we now call the Christmas season. Christmas is a tradition which is celebrated in most Christian sects and faiths.
Let's start with Three Kings Day, also (and more appropriately) known as the Epiphany.
The Epiphany is a feast, celebrated on January 6th. It honors four significant areas or events, in the following order of importance: 1) Baptism of the Lord Jesus Christ, 2) Christ's first miracle - the changing of water into wine at the wedding in Cana, 3) the Nativity of Christ, and 4) the visitation of the Wise Men or Magi. Each of these are significant revelations of God to man - At Christ's Baptism, the Holy Spirit descends and the voice of God the Father is heard declaring that Jesus Christ is His son; at the wedding in Cana, the miracle reveals the divinity of Christ; at the Nativity, the angels bear witness that Christ has come, and the shepherds, representing the people of Israel, bow down before Him; and at the visitation of the Magi or Three Kings, Christ's divinity is revealed to the Gentiles—the other nations of the earth. There are sects within Christianity who have additional witnesses of these events documented.
Over the centuries, different sects have split up these celebrations to give more emphasis on each of them on different Sundays or in different ways. Eventually the Nativity was separated out (mainly in the Western countries) and designated as "Christmas", and is celebrated 12 days before Epiphany.
In Spain on Three Kings Day, children leave their polished shoes outside the door and anticipate the Three Kings coming in the night to leave gifts in their shoes (in more congested cities, they leave their shoes outside their bedroom door or near the front door inside their home). If they have not been good, traditionally they get coal (which is really a black sugared candy). Then there is a very large feast which lasts all day. One particular food that is served is a "Kings Cake", in which they hide a tiny baby Jesus or a ring inside. Whoever gets the figure or the ring, gets to wear a crown for a day and is said to have good luck that year. There are many variations of Three Kings Day in other countries. It's so fun to look these up and tie them to your ancestral countries or religions of origin! Perhaps you have a missionary serving somewhere and want to know more about the traditions of the people in that country, or perhaps you want to or have traveled to another country.
So what are the "Twelve Days of Christmas"?
First, the Twelve Days of Christmas is not the Advent and does not come before Christmas. It is a celebration that lasts for 12 days, beginning Christmas day. It marks the beginning of the Christmastide and the countdown to the Epiphany. In modern Christian sects, it involves the giving of 12 small gifts over the 12 days.
Then what IS the Advent?
The Advent lasts the four Sundays leading up to Christmas and usually begins on the Sunday that falls between November 27th and December 3rd each year. The Advent started as a 40 day preparation for the Epiphany, which included fasting and prayer. The reason it was so significant is because it was not in preparation for the birth of the Savior, but rather a preparation for the baptism of new Christians which was to take place during the Epiphany. In Spanish (and other Latin-based languages), the word "mas" generally means "more". "Christ-mas" = more Christ, or in the sense of the celebration of the Epiphany - more Christians.
Roman Christians in the 6th century tied the Advent to the Second Coming of Christ (or anticipation of Christ's second coming). Today, most Christian faiths bring the two together - they look back on the birth of Christ while also looking forward to the Second Coming of Christ. In European countries, it is not uncommon to see people giving gifts beginning on Christmas day, continuing for 12 days with smaller gifts, and then giving larger gifts again on January 6th.
My disclaimer: I know there are many variations and beliefs among Christian sects, and there is definitely a ton more information available on these topics - each can go into great depth! This post is not designed as a complete study on Christmas, Epiphany, and Advent - nor is it intended to be disrespectful to any faith or incite arguments about religion. This is just a summary of our research and we had a lot of fun discussing and learning about both cultural and religious celebrations!