What is a Mezuzah? The Mezuzah is two chapters from the Torah written in Hebrew, on a piece of parchment. The parchment is then rolled into a scroll, wrapped in paper or plastic, inserted into hard plastic, glass, wooden or metal case, and affixed to the doorpost.
The essence of the mitzvah of Mezuzah is the concept of the Oneness of G-d. The very first verse written on the Mezuzah is the Shema: "Hear oh Israel, the L-rd is our G-d, the L-rd is One." When we pass a doorpost, we touch the Mezuzah and remember that G-d is One: a Oneness that is perfect and unique, a Oneness that is not one of many, nor one of a species. G-d is One without parts, partners, copies, or any divisions whatsoever.
In Enlgish, the Torah verses translate to :
Hear O Israel, G-d our Lord is G-d the Only One. You shall love G-d with all your heart, with all your soul and with all your power. These words which I command you today shall be on your heart. You shall teach them to your children and you shall speak about them when you dwell in your house, when you travel on the road, when you lie down and when you arise. You shall tie them as a sign on your arm and as a head ornament between your eyes. You shall inscribe them on the doorposts of your home and your gates. ( Deuteronomy 6:4-9)
And it shall happen, if you obey my commandments which I command you today, to love G-d within all your hearts and all your souls that I will give the rains of the land in its proper time, the light rains and the heavy rains, and you will gather your grain, your wine and your oil. I will give grass in your fields for your livestock. You will have enough to eat and you will be satisfied. Guard yourselves, lest your hearts lead you astray and you will serve other gods and you will bow to them. G-d will then become angry with you and will withhold the rain, and the land will not produce its bounty. You will quickly be lost from upon the good land that G-d has granted you. You shall place these words on your hearts and on your souls. You shall tie them as a sign on your arms and they shall be head ornaments between your eyes, and you shall teach them to your children to speak about them when you dwell in your house, when you travel on the road, when you lie down and when you arise. You shall inscribe them on the doorpost of your houses and your gates. So that you and your children may live many years on the land that G-d has promised to your forefathers, as many as the days that the heavens are above the earth. (Deuteronomy 11:13-21)
How is a Mezuzah Made? A Mezuzah must be handwritten with a quill and natural ink. Each letter must be written precisely, preferably by a certified sofer (scribe), as one letter written incorrectly would render the scroll invalid. The scripture is written in a single column on 22 scored lines (as there are twenty-two letters of the Hebrew alphabet).
On the reverse is written Shaddai , one of the names of G-d. The parchment should be rolled into a scroll such that the first words " Shema Yisrael" ("Hear O Israel...") will be read first upon unrolling.