The
mezuzah (in Hebrew מְזוּזָה) is a piece of parchment in Hebrew called a klaf, which is held on the doorpost within a protective and often decorative case. It is carefully inscribed by a person known as a Sofer Stam with specific Hebrew verses from the Torah (Deuteronomy 6:4-9 and 11:13-21[1]). The verses on the parchment are those of the
Shema, "Hear, O Israel, Jehovah (is) our God,
Jehovah is One", etc. Jews affix a mezuzah on their doorposts (often both inside and out), in order to fulfill the commandment to "write the words of God on the gates and doorposts of your house" (Deuteronomy 6:9). Bathrooms, laundry rooms and closets are the exception, as they are not considered proper living spaces.
The Sofer Stam (scribe) who writes the words on the
Klaf undergoes special training in the halacha regarding the writing of holy texts as well as the unique skills of carving the quill and the specific style of writing. Written in black indelible ink using a special quill pen usually made from a feather. The parchment with the Shema on it is rolled up and slipped inside its case. The process of putting up a mezuzah is also a special ceremony and involves a blessing and is done in a particular way and attached to a specific place on the doorpost. The parchments are then checked by a knowledgeable scribe or similar, usually a Sofer stam, for signs of fading or tearing or other damage every so often (twice every seven years is standard). A print or photocopy of a mezuzah scroll is not valid, it has to be an original parchment written on by hand by a Sofer Stam scribe.
The case may be made out of a variety of things, from clay, to wood, to metal, plastic, etc, the main thing being that it protects the scroll in a respectable way. Many people enjoy getting mezuzah cases that decorate the doorway, functioning as home decor in addition to keeping the scroll safe. This is a lovely way to beautify the Judaica item and the commandment to put them up. Other customary things to have on the scroll are the word "Shadai" on the back, one of the many names of God, and also an acronym for "shomer dlatot yisrael" or "Guardian of the doors of Israel", and the phrase "כוזו במוכסז כוזו" which can be found on hassidic Ashkenazi scrolls. It is a Caesar cipher, a one letter shift for these words of the Shema: "Adonai, Eloheinu, Adonai", "The Lord, our God, the Lord". Sephardic customs prohibit this addition.
What the mezuzah contains, in short, is a unique parchment written by hand using techniques as old as time, with words from the Bible symbolizing our connection with God. This is a very special piece of Judaica, and as such, many people like to make the case beautiful as well as protective.