All gifts are appreciated, and if you’re new to or unfamiliar with certain Jewish gifting traditions, it’s important to note that the number 18 holds special significance. Gematria, an ancient system of Hebrew numerology, assigns a numerical value to each letter of the Hebrew alphabet. In this system, the word chai (pronounced like "hi," not like the tea) means "life" and is composed of two letters whose values total—yes, you guessed it—18.

Given the importance of chai in Jewish culture, it has become a popular theme for gifts at bar and bat mitzvahs. By giving chai, you are symbolically bestowing the gift of life upon someone.