Price Of Gas

I noticed that gas prices have been coming down.  Who sets the price of gas?  Do you think it is somehow controlled by the government?  I don't know why it goes up and down as it does.  Just four years ago gas was about half the price that it is now.  Back then we thought prices were high and now we are accustomed to high prices.  Why do we look at the recent price drop and think it's so great?  It is still well over $3 per gallon.  That is a terrible price.  I hope it continues to drop in price.