The little box on the door(s) is called a mezuzah, Michelle.
If you are ever in a "Judiaca" shop (or any Christian bookstore with a good Messianic section), you will be able to see one.
They are traditional, but based directly on the Scripture which is so fundamental that it is widely known simply as the 'Shema' in Hebrew -- Deut. 6, starting in verse 4:
"Shema, Yisrael, YHVH Elohenu, YHVH Echad..."
which in the King James English is,
Hear, O Israel! The Lord our God, the Lord is One!
It continues:
And thou shalt love the LORD thy God with all thine heart, and with all thy soul, and with all thy might.
And these words, which I command thee this day, shall be in thine heart:
And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up.
And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes.
And thou shalt write them upon the posts of thy house, and on thy gates.
And these verses are literally put into the mezuzah, so that people are reminded of them, as they "come in" and "go out" of their houses.
Blessings,
Mark