Hashem is a Hebrew term for God. Literally, it means “the name.” In the Bible the Hebrew word for God is made up of four letters, and according to tradition it was only pronounced on Yom Kippur by the High Priest. Saying God’s name was considered a very serious and powerful thing, so much so that one of the Ten Commandments prohibits us from saying God’s name in vain. As a result, people have come up with various substitutions.

When reading Torah, we generally substitute the word Adonai for the four letter un-pronounceable name of God. Outside of reading Torah and praying, God is often referred to as Hashem, a creative way of not saying God’s name.

There are many other names for God in Jewish tradition, including Adoshem, Yah, Yahweh, HaKadosh Baruch Hu, El Shaddai, Av Harahamim, and Harahaman.

Writing "G-d" instead of God is a fairly recent custom in America. Many believe this to be a sign of respect, and the custom comes from an interpretation of the commandment in Deuteronomy 12:3-4 regarding the destruction of pagan altars. According to the medieval commentator, Rashi, we should not erase or destroy God’s name and should avoid writing it. In a Responsa (legal opinion) by the Central Conference of American Rabbis, the primary prohibition against erasure of the name God applies to the sacred names in a written text of Torah. With the advent of computers and the internet, rabbinic authorities have debated whether or not this applies to what is typed on a computer or read on a screen. Most have concurred that it does not apply.