The Haggadah (Hebrew, meaning “telling”) is a guide for the Passover Seder, which remembers the Jewish exodus out of Egypt.
It includes blessings, songs, narratives, prayer, and information about how to do the Seder.
There are many different versions of the Haggadah. Most Haggadot start with instructions for the order of the Seder (usually about 15 steps). Other common elements include the Four Questions (Ma Nishtana) and the song Dayenu.
There are some famous historical Haggadot.
Text adapted from English Wikipedia, Creative Commons Attribution-ShareAlike License 4.0.
Israeli Jewish Passover by Ofir.1970 via Wikimedia Commons, CC-BY-SA 3.0.