The fact that we dip the karpas is a sign of royalty, while we are simultaneously reminded of the bitterness of enslavement by dipping in salt water.  This behavior may confuse the children and may arouse their curiosity.  This will put them in the proper frame of mind for the answers that we will recite in Maggid.

Everyone takes a small piece (less than 1 ounce) of vegetable (celery is customary), and dips it into salt water.

When reciting the  berachah of האדמה one should  also have in mind to include the marror.

Karpas –  כרפס
We dip a vegetable in salt water. The salt water that we use for karpas symbolizes the tears that the Jewish people shed during their enslavement in Egypt.  Salt water also symbolizes the bitterness of the harsh forced labor that the Jews endured in Egypt. 

A. Our custom is to use celery for karpas because celery is called karpas in Arabic. The letters of the word karpas reversed, ס פרך , resent the 600,000 Jews who were slaves in Egypt working עבודת פרך , harsh forced labor, for Pharaoh. (In numerical value, the letter samech = 60 and 60 x 10,000 = 600,000). 

B. The leader should recite the berachah  of Ha’adamah aloud and have in mind to be motzee all those assembled.  One must also bear in mind that this berachah of Ha’adamah should include marror that will be eaten later that night.

C. If one did not have this in mind, however, he does not have to repeat the berachah on the marror.

D. One should be careful to eat less than a k’zayit (1 ounce) of karpas so as not to obligate oneself to say Borei Nefashot.

E. If he did eat a k’zayit, however, he should not recite Borei Nefashot; rather he must wait until Barech and have the karpas in mind during Bircat HaMazon.

F. Even if one inadvertently recites Borei Nefashot, he does not repeat the berachah on the marror.

G. Two different vegetables should be used for karpas and marror. 

H. When the Seder occurs on Friday night, the salt water should not be prepared on Shabbat but rather it should be substituted with vinegar or prepared in advance. If necessary, a small amount may be made.

 I. We are not obligated to lean during karpas.