1. The act of giving red envelopes, or "hongbao," is a long-standing Chinese custom, typically practiced during festivals, weddings, and other significant events.

2. The red color of the envelope symbolizes vitality and good fortune, with the act of passing out hongbao representing the sharing of blessings and good luck.

3. It is customary for the amount of money inside the hongbao to be a double digit, as this is believed to bring twice the happiness and prosperity.

4. When receiving a hongbao, proper etiquette dictates that it should not be opened in the presence of the giver, especially if they are older.

5. The amount of money in a hongbao should be determined by the occasion and the relationship between the giver and receiver, with even numbers being the preferred choice for their association with good fortune and luck.

6. By "double numbers," it refers to numbers that end in an even digit, such as 3000, which is considered an unlucky number in terms of etiquette.

7. Numbers 4 and 8 should be avoided in hongbao as they sound similar to "die" and "leave," respectively, in Chinese, which is considered unlucky.

8. While the amount in a hongbao may not always adhere to these strict rules, simply being mindful of basic etiquette and avoiding numbers with negative connotations is enough to convey good wishes to the recipient.

9. The timing and purpose of giving hongbao vary, but it is commonly seen during festivals, weddings, or on the birthdays of the elderly.

10. During the Spring Festival, the distribution of hongbao symbolizes the wish for a prosperous year ahead, expressing wishes for health and longevity to elders, gratitude to parents, and a smooth growth to children.