Party favor

A party favor or party favour (see spelling differences) is a small gift given to the guests at a party as a gesture of thanks for their attendance, a memento of the occasion, or simply as an aid to frivolity.

It is traditional in some Western cultures for the guests at bridal showers and weddings to receive party favors; these vary in price and durability in accordance with the desires and budget of the host or hostess. This practice has spread to many other formal occasions such as baby showers, engagement parties, retirement parties, anniversaries, and holiday gatherings.

For small social gatherings such as birthday parties, guests may receive a simple and inexpensive favor such as a small toy. In some cases guests might receive a small "gift bag" with a handful of favors toys or trinkets, candy, pencils or other small gifts. Occasions such as birthday parties, seasonal parties, unique events such as a Bar/Bat Mitzvah or Christening are a few social gatherings where favors may be appropriate.

Wedding favors are small gifts given as a gesture of appreciation or gratitude to guests from the bride and groom during a wedding ceremony or a wedding reception.

The tradition of distributing wedding favors is a very old one. It is believed that the first wedding favor, common amongst European aristocrats, was known as a bonbonniere. A bonbonniere is a small trinket box made of crystal, porcelain, and/or precious stones. The contents of these precious boxes were generally sugar cubes or delicate confections, which symbolize wealth and royalty. (In this era, sugar was an expensive commodity and was treasured only among the wealthy. It was believed that sugar contained medical benefits). As the price of sugar decreased throughout centuries, the tradition of providing gifts to guests reached the general populace and was embraced by couples of modest means.

...
Wikipedia