Diversification
They allow you to invest in a wide range of assets, reducing risk. This allows an investor to buy an entire index or an entire sector at the click of a button, allowing the investor to hold hundreds of stocks or bonds at very low cost.
Low costs
Here is one of the biggest advantages. When buying hundreds of shares, an investor would often pay a relatively high amount in fees. Here, however, you pay one fee per purchase and then a management fee (TER) each year. However, this is often very minimal due to the high competition, gradually becoming very close to zero. However, higher fees are associated with higher-risk ETFs.
Liquidity
ETFs are tradable like shares, meaning they can be bought or sold at any time during trading hours. Moreover, in many cases they are some of the most heavily traded instruments ever, and thus have huge volume.
Passive investments
Passive investments are very simple, many people are either given a standing order or they just transfer money to a broker and buy the ETF themselves and don't worry any further. Passive investments also minimize dependence on individual managers. They do not require active decision-making by fund managers, which eliminates the risk of human error in decision-making and can minimize the influence of subjective factors on investment performance.