When quoting the price of gold, most business reports will show the price per troy ounce in US dollars. If you are following the market from outside the US, make sure to convert this price into your home currency, and know that one troy ounce is equivalent to about 31.1 grams.
Also note that the price quoted on the market is always for pure gold. Most jewelry is much less than pure (usually between 40-75%), bullion and coins however, are usually fairly high purities (above 90%).
With an understanding of the mechanics behind the price of a physical sample of gold, you can start to look at the market forces that cause the wide daily swings in price. They are listed in order of their impact on the daily price of gold. https://www.a1mint.com/shop/