The Mezuzah & Klaf

Mezuzah: Hebrew for door post, from a root word meaning 'prominent'
Klaf: Hebrew for parchment or scroll, found inside the Mezuzah

The B'rakha (blessing)
Before affixing the mezuzah to the doorpost, the following blessing should be recited:

Barukh atah Adonai, Elohaynu, melekh ha-olam Blessed are you, L-rd, our G-d, king of the universe

asher keed'shanu b'meetzvotav v'tzeevanu leek'boa mezuzah who has sanctified us with His commandments and commanded us to affix a mezuzah

After reciting the B'rakha (blessing), the mezuzah should then be affixed to the upper third part of the doorpost on the right side as one enters the house or room. If the doorpost is wide enough to permit, the mezuzah should be tilted with the upper part slanting inward toward the house or room.

If you were to open the mezuzah, you would find a small klaf (parchment) written in Hebrew by a sofer (trained scribe). The front side of the klaf contains two portions of scripture from the book of D'varim (Deuteronomy) (6:4-9, 11:13-21) found in Torah. The back of the parchment contains the word "Shaddai" which means "Almighty," but also stands for "shomer delatot yisrael" which means "guardian of the doors of Israel." If you place the parchment in the mezuzah case yourself, roll it from left to right so that the word Shaddai faces out. If your mezuzah has an opening, Shaddai should appear in it, otherwise align the word with the front of the case.

The Mezuzah and klaf are used to dedicate the dwelling to Adonai our G-d. Jews have been putting mezuzot on the doors of their houses since biblical days. We read the commandment concerning the mezuzah every time we read the Shema: "inscribe them [these words] on the doorposts of your house and on your gates." The mezuzah reminds us of our relationship to God every time we leave our houses and every time we return. Here is an English translation of both portions of Torah:

D'varim (Deuteronomy) 6:4-9
"Hear, O Israel: Adonai our G-d, Adonai is one. Love Adonai your G-d with all your heart and with all your soul and with all your strength. These commandments that I give you today are to be upon your hearts. Impress them on your children. Talk about them when you sit at home and when you walk along the road, when you lie down and when you get up. Tie them as symbols on your hands and bind them on your foreheads. Write them on the door frames of your houses and on your gates."

D'varim (Deuteronomy) 11:13-21
"So if you faithfully obey the commands I am giving you today -- to love Adonai your G-d and to serve him with all your heart and with all your soul -- then I will send rain on your land in its season, both autumn and spring rains, so that you may gather in your grain, new wine and oil. I will provide grass in the fields for your cattle, and you will eat and be satisfied. Be careful, or you will be enticed to turn away and worship other gods and bow down to them. Then Adonai's anger will burn against you, and he will shut the heavens so that it will not rain and the ground will yield no produce, and you will soon perish from the good land Adonai is giving you. Fix these words of mine in your hearts and minds; tie them as symbols on your hands and bind them on your foreheads. Teach them to your children, talking about them when you sit at home and when you walk along the road, when you lie down and when you get up. Write them on the doorframes of your houses and on your gates, so that your days and the days of your children may be many in the land that Adonai swore to give your forefathers, as many as the days that the heavens are above the earth."