The seder officially begins with lighting the candles. In Jewish tradition, lighting candles and saying a blessing over them marks a time of transition, from the day that is ending to the one that is beginning, from ordinary time to sacred time. 

בָּרוּךְ אַתָּה אֲדֹנָי אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ לְהַדְלִיק נֵר שֶׁל [שַׁבָּת וְשֶׁל] יוֹם טוֹב


Baruch Atah Adonai Eloheinu melech ha'olam asher kid'shanu b'mitzvotav, v'tzivanu l'hadlik ner shel (Shabbat v'shel) Yom Tov.


Blessed are You, Adonai our God, Ruler of the Universe, who has sanctified us with laws and commanded us to light the festival lights.


haggadah Section: Introduction