Oil is arguably the most important commodity in the world today. The commodity and its derivatives make their way into essentially every application of modern life, from transportation and gasoline to plastics. Because of its vast applications, oil has also become one of the most heavily-traded commodities on the market, offering investors both the necessary levels of volatility and liquidity needed to make a lucrative trade. And thanks to the rapid expansion of the exchange-traded fund industry, investors now have several ways to gain access to the arguably most useful commodity in the world. Below, we outline the three most popular oil ETFs and which one will fit your investment objectives [for more oil news and analysis subscribe to our free newsletter].