ETF stands for "Exchange Traded Fund" which means that it is a security that tracks a fund or "bundle of assets". Similar to a mutual fund in some ways, and ETF gets traded just like a stock does. This makes it prone to daily price fluctuations, but is a great vehicle for traders as there is high liquidity and low fees.

The ETF fund itself actually OWNS the underlying asset and then divides that asset up into individual shares. This gives investors the opportunity to invest in the asset without having to actually hold it themselves. Basically it is an indirect way to invest in something without having to manage it or hold it yourself.