From Wikipedia:

A mezuzah (Hebrew: מְזוּזָה‎ “doorpost”) (plural: mezuzot (מְזוּזוֹת)) is a piece of parchment (often contained in a decorative case) inscribed with specified Hebrew verses from the Torah (Deuteronomy 6:4-9 and 11:13-21).

These verses comprise the Jewish prayer “Shema Yisrael”, beginning with the phrase: “Listen, Israel, the Lord is our God, the Lord is One.”

A mezuzah is affixed to the doorframe of Jewish homes to fulfill the mitzvah (Biblical commandment) to inscribe the words of the Shema “on the doorposts of your house” (Deuteronomy 6:9).

Jewish law requires a mezuzah on every doorway in the home apart from bathrooms, and closets too small to qualify as rooms; but many families only place one in the front doorway.

The parchment is prepared by a qualified scribe (a “sofer stam”) who has undergone many years of meticulous training, and the verses are written in black indelible ink with a special quill pen. The parchment is then rolled up and placed inside the case.

From Gifts for Home – Jerusalem gifts

From Gifts for Home – Jerusalem gifts

From Gifts for Home – Jerusalem gifts