The word "Torah" literally translates as law or teaching.

Torah is the Five Books of Moses: Genesis, Exodus, Leviticus, Numbers and Deuteronomy. Each book is one-fifth of the Torah. In Hebrew, this is collectively called the Chumash (literally: fifth).

It is called the Five Books of Moses because G-d dictated the text to Moses, who then wrote it down. Moses also plays a central role in the Torah.

Sometimes you will see the Five Books referred to by the Greek word, Pentateuch, which means "Five Books." ("Pent" means five, and "teuch" means book.)

The second, more colloquial use of the term "Torah" includes the entire body of rabbinic literature - the Five Books of Moses, the Prophets and Writings, the Midrash, the Talmud (the compilation of rabbinic teachings explaining the biblical commandments), and even any teaching today based on these sources.

In this regard, Torah is the "constitution" of the Jewish people, covering the totality of law and lore, including lifecycle, business and medical ethics, holidays, family life, etc.

So when someone says, "I'm going to a Torah class," or shares a "Devar Torah" (word of Torah), it is usually meant in the broader sense, not the Five Books in particular.