What is written inside a mezuzah?

The first two paragraphs of the Shema (Deuteronomy 6:4–9 and 11:13–21), handwritten in ink on parchment by a trained scribe. A printed paper is not a kosher mezuzah.

Which side of the door does it go on?

On the right side as you walk into the room, in the upper third of the doorpost.

Do I need a mezuzah if I rent?

Yes. In Israel a tenant puts up mezuzot right away; outside Israel the obligation for a rented home begins after 30 days, though many put them up on moving in. Ask your rabbi about the blessing.

Is a mezuzah a good-luck charm?

Its purpose is the commandment and the reminder of God’s unity at every entrance. The Talmud does speak of God protecting the house, but the Rambam warns against treating it as an amulet.

Mezuzah – what it is and how to put one up מְזוּזָה

A mezuzah is a small parchment scroll, handwritten by a scribe, containing two passages of the Torah – the first two paragraphs of the Shema – which is fixed to the right doorpost of a Jewish home.

The source

The commandment appears twice in the Shema: “and you shall write them on the doorposts of your house and on your gates” (Deuteronomy 6:9; 11:20). The scroll contains exactly those two passages (Deuteronomy 6:4–9 and 11:13–21), written on kosher parchment with the same rules as a Torah scroll. The case is only a cover; the mitzvah is the parchment.

Where and how

On the right side of the doorway as you enter the room or house.
At the beginning of the upper third of the doorpost height (Menachot 33a; Shulchan Aruch, Yoreh De'ah 289:2).
On every doorway of a room used for living – not on bathrooms or very small storage spaces.
The blessing, said before affixing: “Baruch Atah… asher kidshanu bemitzvotav vetzivanu likbo’a mezuzah.” One blessing covers several mezuzot put up at the same time.
A mezuzah should be checked by a scribe twice in seven years (Yoma 11a), since letters can fade or crack.

Sephardi and Ashkenazi customs

The Talmud records a dispute whether the mezuzah is placed vertically or horizontally (Menachot 33a, Rashi and Rabbeinu Tam). Ashkenazim follow the Rema and fix it slanted, top towards the inside of the room, as a compromise; Sephardim follow the Shulchan Aruch and fix it upright. Scribal styles of the letters also differ (Beit Yosef, Arizal and Alter Rebbe scripts).

Sources

וּכְתַבְתָּם עַל־מְזוּזֹת בֵּיתֶךָ וּבִשְׁעָרֶיךָ
Deuteronomy 6:9

Talmud and halachic sources

Talmud, Menachot 31b–34a – how the mezuzah is written and placed
Talmud, Menachot 44a – a rented home outside Israel (after 30 days)
Shulchan Aruch, Yoreh De'ah 285–291

Frequently asked questions

What is written inside a mezuzah?: The first two paragraphs of the Shema (Deuteronomy 6:4–9 and 11:13–21), handwritten in ink on parchment by a trained scribe. A printed paper is not a kosher mezuzah.
Which side of the door does it go on?: On the right side as you walk into the room, in the upper third of the doorpost.
Do I need a mezuzah if I rent?: Yes. In Israel a tenant puts up mezuzot right away; outside Israel the obligation for a rented home begins after 30 days, though many put them up on moving in. Ask your rabbi about the blessing.
Is a mezuzah a good-luck charm?: Its purpose is the commandment and the reminder of God’s unity at every entrance. The Talmud does speak of God protecting the house, but the Rambam warns against treating it as an amulet.