Yod is the tenth letter of the Hebrew alphabet.

The gematria of Yod is 10.

Up until Yod, there are the single integers of the Alefbet (alef-beis). It's the realm of two-digit numbers. After the yud, each let­ter’s gematria increases by ten instead of one. Yud is ten, kaf is twenty, lamed is thirty, mem forty, and so on. In Judaism, the number ten is quite significant. Throughout the teachings of Torah, Talmud, Kabbalah and Chassidus, the number ten is a fundamental building block for every aspect of Creation.

Firstly, there are the Ten Utterances of Speech through which G‑d created the world. Next come the ten generations from Adam to Noah, and the ten generations from Noah to Abraham. There were ten plagues that G‑d brought upon the Egyptian people, and ten miracles that He performed for His people to save them from those plagues. G‑d challenged the Jewish people with ten tests in the desert. And, of course, G‑d gave us the Ten Commandments.