When I was a child, my mother made sure we had an advent calendar to open starting on December 1st. I'm pretty sure some years we would reuse the one from the previous year, but it was still fun nonetheless.
Let me tell you a little bit about advent calendars to hopefully give you an idea of what they are. While the answer may be obvious to some, advent calendars are not nearly as popular as other Christmas decorations or activities such as Christmas lights, or putting up the tree.
An advent calendar is a calendar that starts on December 1st and ends on December 25th. It represents a count down to Christmas. There are also calendars that start on the First Sunday of Advent (the 4th Sunday before Christmas). Advent is an observation among numberous churches who worship Christianity. It is the the time that Christians prepare for the celebration of the Nativity. Many children like use this calendar as a way to track when Santa is coming.
Today, advent calendars come in numerous styles. Check out this Today article for a good idea of the variety of advent calendars you have available out there for purchase.
As a kid, we would have a cheap cardboard calendar, which would allow you to open a flap each day to reveal a Christmas themed scene. They still make these and yes they are still super fun for kids, at least mine. Today, there seems to be endless options that make choosing just one super difficult. As a primer to advent calendars I do not intend on getting into the details of specific advents. However, I hope now understand the idea behind advent calendars.
