Washing your hands - mostly from Wikipedia:

Washing before a meal (Mayim Rishonim = First Waters) AKA Ntilat Yadayim:

In the Babylonian Talmud, washing before meals is seen as so important, that neglecting this risks sudden destruction or poverty. Let's discuss why washing hands before eating is/was considered so important. We can talk also about ritual purity. 

Washing after a meal (Mayim Acharonim = Last Waters):

It is now not so common, but in Talmudic time, one is supposed to also wash ones hands after the meal. This may have been because the food was preserved using a type of salt which was dangerous to get into the eyes. It may also be because of the blessings after meal, and the wish to have clean hands before saying G-d's name. 

Although  mayim acharonim  was once not widely practiced (for example, until recently it did not appear in many Orthodox Passover Haggadot) it has undergone something of a revival and has become more widely observed in recent years, particularly for special meals such as Shabbat and Festivals. Some denominations have supported discontinuing the practice of  mayim acharonim  on the grounds that the rabbis of the Talmud instituted it as a health measure, and since modern foods no longer contain preservatives so dangerous as to cause blindness upon contact with the eyes, washing the hands after meals is no longer required and can be discontinued by contemporary rabbinic decision.

Tonight, we've emphasised washing after the meal above washing before the meal, as a result of our reverse seder!


Blessed are you, O Lord, our God, King of the Universe, who has sanctified us through your commandments and has commanded us concerning the washing of hands"  

בָּרוּךְ אַתָּה הָ׳ אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ עַל נְטִילַת יָדַיִם ‎

haggadah Section: Introduction