The Mezuzah: (Lit. “doorpost”): A small parchment scroll upon which the Hebrew words of the Shema are handwritten by a scribe. Mezuzah scrolls are rolled up and affixed to the doorposts of Jewish homes, designating the home as Jewish and reminding those who live there of their connection to G‑d and their heritage.
The decorative case containing the mezuzah scroll is just that: a mere container. What’s important is the scroll. Every single letter in the mezuzah must be properly formed. A single crack in the parchment or any omission can invalidate the entire scroll. A printed mezuzah is invalid. For this reason it is vital that it be purchased from a reputable scribe or retailer.
On the reverse side of the scroll, the scribe writes one of G‑d’s names: Sha-dai. The three letters of this name form an acronym for the Hebrew words that mean “Guardian of the doorways of Israel.” Since this name of G‑d begins with the letter shin, mezuzah cases are often decorated with that letter.
You should hang a mezuzah on just about every doorway that belongs to you. Notable exceptions are doors leading to bathrooms and small closets.
The mezuzah should be hung on the right side of the door, on the top third of the doorway. The mezuzah should be right-side up, and slanted so that the top of the mezuzah faces inwards towards the room.
The mezuzah on the doorpost reminds those who walk through that G‑dly life and Torah accompany them wherever they go.
Our sages teach that a mezuzah has the unique property of protecting the inhabitants of the home where it is hung—whether the inhabitants are inside or outside that home. The Talmud teaches that while most kings sit on the inside while their guards protect them from without, G‑d stations His protection (as manifested in the mezuzah) on the outside, protecting His beloved people.
G‑d promises that anyone who carefully observes the mitzvah of mezuzah will lead a longer, richer life, as will their descendants.
When passing through a doorway where a mezuzah has been affixed, we glance at it and touch it. Some people then kiss their fingertips. This serves as a reminder throughout the day that G‑d is always with us, inside or outside our homes.
We get our Mezuzot from New York and the cost-price is $36 (case included).