In the White
I have noticed in previous years at synagogue on Yom Kippur that many people wear white clothes, or a type of white robe, and sometimes even white shoes. What's that all about? I imagine it has something to do with appearing pure before the Almighty, but any additional explanation you can offer would be appreciated.
Many have a custom of wearing white clothing on Yom Kippur as an expression of emulating the ministering angels who are described as serving G-d in clean, white "garb". This is practiced by both men and women.
Some men wear a white robe over the clothing, called a kittel in Yiddish. Because it is similar to a burial shroud, it also serves to remind us of man's mortality and the need to do teshuva, or repentance, before one's life expires.
Whether one wears regular festive clothing, or some form of white clothing, one should not wear gold, or have gold-colored decoration on the clothing. This is because gold recalls the sin of the golden calf, and that which recalls sin should not be worn as we pursue forgiveness. Silver is permitted to be worn, or embroidered on the kittel, as silver is similar to white and symbolizes purity and mercy.
In addition, it is a widespread custom for men to wear the large white prayer shawl, the tallit gadol, on the evening of Yom Kippur. This also is to convey our desire to be "angelic" in our single-hearted devotion of G-d, recalls being wrapped in a burial shroud, and conveys purity and mercy. The tallit is put on while still day in order to be able to recite a blessing upon donning it, since at night no blessing is recited for the tallit. This is usually done at home, before going to the synagogue, at which time fathers, enveloped in the large white tallit, movingly bless each of their children to be sealed the Book of Life.
Since wearing leather shoes is prohibited, and that's in order that we should not be deriving benefit from loss of life at the very moment we are beseeching G-d for renewed life, many buy special shoes for Yom Kippur made of cloth or some other material. And since these are special "Yom Kippur" shoes, many buy white ones.
A righteous rabbi once addressed his congregants moments before the onset of Yom Kippur with the following words on the topic of wearing white:
"My brothers, take it to heart that it is in white garments like these we are wearing now that we shall ascend to Heaven to be judged and give accounting before G-d. Let us then imagine that we are standing in this clothing before the Throne of Glory now, on this day of judgment - Yom Kippur. We should have true remorse today, because one who actually appears before the Throne on the day of death most certainly feels remorse. But the difference is that repentance does not avail after death – only now that we are still alive. Let us then truly regret our sins, and accept upon ourselves to sin no more, and let us plead to the King who grants forgiveness that He grant us forgiveness and atonement."