According to Encyclopedia Britannica :
Las Posadas, ( Spanish: “The Inns”) religious festival celebrated in Mexico between December 16 and 24. Las Posadas commemorates the journey that Joseph and Mary made from Nazareth to Bethlehem in search of a safe refuge where Mary could give birth to the baby Jesus. When they were unable to find lodging in Bethlehem, Joseph and Mary were forced to seek shelter in a stable, where the Christ child was born.
In general, for Guatemalans las posadas indicates the beginning of the Christmas season. The distinctive sound of the turtle’s carapace reverberate in the nighttime air. The smell of ponche sweetens the streets.
The Posadas are like tiny processions that symbolize the journey of Mary and Joseph from Nazareth to Jerusalem and their search for a place to spend the night. This tradition originates in Spain where they are called Jornadillas and this tradition is typical of many Latin American countries. Posadas are celebrated in Guatemala from December 16th to the 24th.
The posadas start off small and gather more and more people as they walk, until a large crowd is walking through the streets by the evening. People carry candles protected by cellophane and sing hymns as they walk. When the procession arrives at each house, they ask for posada (accommodation, lodging) you can see as they progress to different houses, they are at first denied and then welcomed in, blessing the last house as they enter.
When peopel enter, they will be offered food and drink, the type depending on the economic status of the house.