Closed end funds issue shares only once - at the time of formation, after that, new investors have to buy shares from existing owners. As a result, closed end funds' share prices fluctuate with supply and demand, not exactly track the underlying assets.
It's common for close end funds trade at a wide discount or premium to its net asset value (NAV), as an investor, you want to buy closed end funds trade at a discount to NAV.
Because closed end funds don't have fluctuation of cash flows, it can invest in illiquid assets or borrow to boost returns, while most mutual funds are barred from doing.
An example of a closed end fund is CBRE Clarion Global Real Estate Income (IGR).