A lectionary is a pattern for reading Scripture. It offers a three-year cycle, with the gospels of Matthew, Mark, and Luke providing the basis of each cycle. Selections from John are read during Eastertide in each year. The lectionary doesn’t read straight through the Bible. Instead it is used as a guide in services of worship across denominations, it is a useful tool for choosing and sequencing Scripture readings and related music and liturgy for weekly worship.
The Revised Common Lectionary is built around the seasons of the Church Year, and includes four lections for each Sunday, as well as additional readings for major feast days. During most of the year, the lections are: a reading from the Hebrew Bible, a Psalm, a reading from the Epistles, and a Gospel reading. During the season of Easter, the Hebrew Bible lection is usually replaced with one from the Acts of the Apostles. The lections from the Hebrew Bible are sometimes chosen from the Apocrypha.
The gospel readings for each year come from one of the synoptic gospels according to the following pattern:
(Adapted from Vanderbilt Divinity Library, "Frequently Asked Questions," The Revised Commons Lectionary, https://lectionary.library.vanderbilt.edu/faq2.php)
