Today, Wednesday, and this Friday and Saturday, are Ember days in Advent. What is that you ask?
The Ember Days were traditionally a Wednesday, Friday, and Saturday, occurring in Lent, the Octave of Pentecost, after the Triumph of the Cross in September, and in the third week of Advent. These "Quatuor Tempora" had as their purpose, "besides the general one intended by all prayer and fasting, was to thank God for the gifts of nature, to teach men to make use of them in moderation, and to assist the needy." (Old Catholic Encyclopedia: Ember Days).
Specifically, it is traditional on these days to fast and to observe partial abstinence (blood meat only at the main meal) on Wednesday and Saturday, and full abstinence on Ember Friday. This, of course, is not canonically required, beyond the Friday abstinence/penance. This penance and prayer was offered especially for the clergy.
These days, then, four in number, like the seasons, were a time of gratitude, penance, and prayer.
For more on the Ember Days, you might note: Fisheaters: Ember Days
That the practice and celebration of Ember Days has largely disappeared, and is now restricted to traditional communities, is tragic and seemingly contrary to the instructions of Holy Mother Church. Indeed, in the current General Instruction of the Roman Missal, it provides that: "In the drawing up of the Calendar of a nation, the Rogation Days and Ember Days should be indicated (cf. no. 373), as well as the forms and texts for their celebration, and other special measures should also be kept in mind." (USCCB GIRM: Chapter IX)
Perhaps if it is not a custom you have, this is the year it will be revived in your family or parish?
Live well!