Lighting the Hanukkah candles.
The Chanukiah (sometimes called a menorah) is the nine-branched candelabrum that is used on Hanukkah.
Chanukiahs are commonly made out of metal, or stone, and can be purchased at a Judaica store, but they can be made out of anything, and many people choose to make their own.
On the first night of Hanukkah we light the Shamash, which is the candle used to light all the others, as well as one of the other eight candles. Every subsequent night we add another candle, until, on the eighth and final night of Hanukkah all the branches of the Chanukiah are lit. The candles commemorate the original Hanukkah miracle of one container of oil burning for eight days in the time of the Maccabees.
When lighting the Chanukiah we say:
Barukh ata Adonai Eloheinu Melekh haolam asher kidshanu bemitzvotav v'tzivanu lehadlik ner shel Hanukkah.
Praised are You, Lord our God, King of the Universe whose commandments add holiness to our lives and who gave us the commandment to kindle light for Hanukkah.
Barukh ata Adonai Eloheinu Melekh haolam sh'asa nisim la'avoteinu bayamim hahem bazman hazeh.
Praised are You, Lord our God, King of the Universe who accomplished miracles for our ancestors in ancient days and in our times.
On the first night we also say:
Barukh ata Adonai Eloheinu Melekh haolam shehehiyanu v'kiyemanu v'higiyanu lazman hazeh.
Praised are You, Lord our God, King of the Universe for granting us life, for sustaining us, and for enabling us to reach this day.