To commemorate the oil lamps of the Temple's menorah, in which the miracle occurred.
The Seleucids (Syrian-Greeks) under Antiochus Epiphanes (2nd century BCE), at the instigation of the Hellenizers, had forbidden various Torah-practices such as Sabbath-observance and circumcision, rededicated the Temple to a Greek idol, and pressed the Jews to offer up sacrifices to the idol. One of the leading elder Jewish sages called upon the people to keep observing the Torah anyway; and if necessary, to use force in resisting the decrees. When a Hellenized Jew offered a sacrifice to the Greek idols in a nearby village, the sage killed him as well as the Greek overseer. This brought a violent reaction from the Greeks; and the loyal Jews, led by the Hasmonean family, were forced to retreat from their towns and strike out at the Greeks in an attempt to oust them from the Holy Land and to enable the people to once again observe the Torah. The Torah-Jews were heavily outnumbered by the attacking Greek armies, but God gave them miraculous victories again and again. After three years of struggle, the Greek armies retreated from Jerusalem, and the Hasmoneans (also called Maccabees) entered the Holy Temple which the Greeks had defiled, reconsecrated it to God, and began the Temple service once more. Among other things, they wanted to relight the olive oil candelabrum (Exodus ch. 25), but could only find one day's supply of undefiled oil - and it would take eight days to make and bring some more.
Miraculously, the menorah stayed lit for eight days (Talmud, Shabbat 21b), allowing enough time for new oil to be prepared and brought. The significance of the miracle is that it demonstrated that God's presence was still there. The Torah-community was overjoyed, because God's presence meant everything to them.
This is what Hanukkah represents: the closeness to God; and the avoidance of Hellenization (assimilation).
The Torah Sages instituted the festival of Hanukkah at that time (Talmud, Shabbat 21b), to publicize the miracle (Rashi commentary, ibid). This is why we light our Hanukkah-menorahs.
(The Hanukkah-menorah, or hanukkiyah, is a special form of the original seven-branched menorah. Our Hanukkah-menorahs have eight spaces for oil, or candles, to mark each of the eight days for which the oil lasted and a ninth to hold the shamash, a candle used to light the others.)
The Al-Hanisim prayer which we recite during Hanukkah centers around the Hasmoneans' victory and rededication of the Temple, while the candle-lighting commemorates the miracle of the oil.
Though the military victory is prominently mentioned in the prayers, it wouldn't have been celebrated if not for the miracle of the oil. It should also be noted that the main goal for which the Maccabees fought was not political independence. They fought to enable the people to observe the Torah's commandments; as we say in the Al Hanisim prayer: "The Greeks sought to cause us to forget Your Torah and leave Your statutes."
It is called the shamash (servant). See also:More about Hanukkah
Eight for the eight days of Hanukkah. The ninth is for the helper-candle used to light the others.
The shamash (helper or attendant) is used to light the Hanukkah menorah or hanukiyah.
The Hanukkah candles don't have names, except for referring to them generically, as neirot Hanukkah (candles of Hanukkah). The one candle which does have a name is the extra one, used to light the others, which is called the shamash (helper).See also:More about Hanukkah
There are 8 days of Hanukkah.
Yes, you light candles on ALL 8 nights of Hanukkah.
They light candles.
You light 9 candles on Hanukkah, and there is no tradition of asking why, unless there are guests in the home who don't know about Hanukkah.
The Hanukkah-menorah holds eight candles. Each night, there is one other candle to the side, which is used to light the others. See also:More about Hanukkah
The candle used to light the other candles on the menorah or chanukiah is called the shamash.
Yes, it is.
During the first half-hour when the candles are burning, there is a custom (not a full prohibition) to refrain from work. Also, the light of the Hanukkah-menorah shouldn't be used for mundane purposes. Other than that, there are no prohibitions specific to Hanukkah.