Exchange-Traded Funds (ETFs) are a type of investment fund that can be traded on stock market exchanges. ETFs can hold many different investment classes like stocks, bonds, cryptocurrencies and commodities.
They are often a pretty diversified type of investment because they invest in multiple assets at the same time.
ETFs are basically a package that allows a specific portfolio to be continuously traded.
The core mechanism of ETFs is creation and redemption. This means that ETFs have to be created by the ETF provider in cooperation with a financial institution. Financial institutions like large banks organize the buying and selling of assets (like stocks) for the ETF provider.
They will buy more assets when demand rises, and will sell securities when demand falls. This in order to keep the price of the ETF close to the value of the underlying assets. This mechanism actually is a little more complicated than we have stated here.
Without this mechanism, the prices of ETFs would not be realistic to their underlying assets, and could be bought and sold for unfair prices.

There are many different types of ETFs in existence. Examples are passive ETFs, active ETFs, bond ETFs, cryptocurrency ETFs and commodity ETFs.
Exchange-Traded Fund fees can be very low if they function more passively like index funds. Their fees can also be higher if they are more actively managed.
Even though Exchange-Traded Funds are marketed as safe investment products, risks do exists. The prices of its underlying assets could fall, and with it the ETF. The ETF could also have errors in its pricing mechanism. There are some other potential risks as well.
Exchange-Traded Funds have become such a popular investment class because they offer low fees, transparency and tax efficiency. They have also changed investing because they allow investors to invest in multiple assets in one package, instead of buying the assets on their own.