(I'm not saying that in an insulting way but most people don't care enough to ask or look)
When you come into contact with gold, you will almost always see it and that represents to you what the majority of it is used for.
Metals like gold can be mixed with other metals to form composites and alloys.
The carat rating of gold is a measure of purity, 24k gold is the most pure form while 12k is only 50% gold.
If you own a car and live in a modern house I can guarantee you that their are things in it which are radioactive and things that are made out of precious metals that you have never thought of.
Want some uranium? It's one of the rarest elements on earth but I'm betting that their may be some under your home.