A mezuzah is a small parchment scroll placed on a Jewish doorpost.
The scroll contains the Hebrew passages Deuteronomy 6:4–9 and 11:13–21, including the command to write these words on the doorposts of a house. A trained scribe writes the text by hand using special rules. The parchment is then placed in a case and attached to the doorpost of qualifying rooms in many observant Jewish homes.
The mezuzah is fixed on the right side of the entrance as one enters, generally at the lower part of the upper third of the doorway. Details of placement and which rooms require a mezuzah are governed by Jewish law and can vary by circumstance.
The case is not itself the mezuzah; the essential religious object is the parchment scroll inside. Decorative cases may be made from wood, metal, ceramic, or other materials, and they come in many styles.