Yom Kippur is the highest holy day of the biblical calendar, God’s calendar.
This web page gives good background of biblical and Jewish traditions as well as wonderful explanations of why this is important to Christians as well. It’s always important that as we read the old covenant scriptures that we can see Jesus (Yeshua)
Yom Kippur – the day of atonement
The biblical Holiday website is a wonderful site for learning the basics, especially good for homeschoolers.