If you have eaten a Shabbat meal at a religious family, you may have noticed that after the meal, before the birkat hamazon blessing, a small bowl and utensil was bought out and passed along the table for those sitting around it to use. Many households observe the ritual of washing hands before benching, the Grace after meals prayer.
This diverse custom is called mayim achronim, the last waters. Unlike the ritual of washing hands before a meal, here, only the fingertips to the joints are washed using a small washing cup and a bowl. Both men and women are obliged to do this commandment however in many households women do not perform this mitzvah.
It was thought to have been originally introduced a precaution to remove the melach sedomit, the Sodomite salt, which was known to be very caustic and if a little particle of it came into contact with the eye, it would cause blindness. Also, the people of Sodom as told in the Book of Genesis were not hospitable and we do not want to be like them so we wash our hands as if to wash any evil thoughts of being inhospitable away and remember to invite guests and be hospitable. Another opinion is that it was used to wash hands before benching, the grace after meal prayer.
Because it is used for the purpose of cleanliness, there is no need to have another person hold the utensil and pour the water or to use the regular hand washing vessel. To perform this ritual, a small vessel is used together with a bowl in which to pour the water. These vessels are usually made from silver and are beautifully decorated with intrinsic designs. Right before the birkat hamazon prayer, the vessel is bought out to the table, along with a towel and is passed around the wall. Whether or not your family observes this ritual, it is a special ritual that has a lot of meaning and interpretations. This is a great gift for an engagement party or wedding gift.