The Hebrew letters of Nes Chanukah, the Miracle of Chanukah alludes to Tzedakah, charity. The numerical value of נס חנוכה equals 199. Likewise, the numerical value ofצדקה equals 199.
Harav Moshe Wolfson zt’l explained, every Minhag Yisrael has deep significance. The minhag of giving gifts on Chanukah is to arouse Hashem to give us gifts - the great light and kedushah that comes with Chanukah.
As the Hasmonean conquest over the Greeks came about through a woman, Yehudis, who served cheese to Holiphornus, the Greek general, that made him thirsty and wine to drink which put him to sleep. As he was sleeping she executed him.
Since the miracle of Chanukah occurred with oil, it is customary to eat foods, such as latkes (potato pancakes) or sufganiyot (doughnuts) which are fried in oil.