Passages of Holy Scripture, saints and events for commemoration are associated with each date, as are many times special rules for fasting or feasting that correspond to the day of the week or time of year in relationship to the major feast days.
The Epistle and Gospel readings at the Divine Liturgy throughout the year are determined by the date of Pascha.
These are feasts which celebrate major historical events in the lives of Jesus Christ or the Theotokos (Virgin Mary).
Because of the complexity created by the intersection of the various cycles, a number of Orthodox institutions will print an annual calendar which contains rubrics for the services during that particular year.
Simpler wall calendars will show the major commemoration of the day together with the appointed scripture readings.