There are a number of different ways that you can invest directly in a commodity, such as oil or gold for example. These tend to seem more difficult to investors in comparison to things like bonds and stocks. A major reason for why investing in gold appears to be more difficult is because bonds and stocks are both readily transferable and are easily accessible for most average investors. Traditionally, commodities such as these seem more difficult to invest in because they are traded more complexly through options and futures markets. You cannot simply buy a barrel of oil or a brick of gold in most cases, for example.
Gold is actually much more accessible to average investors, and so investing in gold may actually be a whole lot more accessible than you would normally assume. This is because as an investor you can essentially purchase gold bullion very easily, which is physical form of gold. You can sometimes buy this gold from a dealer, and other times directly from a bank. With the invention of a variety of other types of financial instruments, it has also become possible for you to buy gold and similar commodities without ever actually buying a physical product. These are all also worth considering as an investor.
One of the options that are available to you when investing is gold is ETF or Exchange Traded Funds. These replicate the movement for whatever underlying commodity you are trading in, which gives you direct exposure as an investor. Not every commodity is going to have an ETF, but gold certainly does. For example, there are ETFs traded on the NYSE or New York Stock Exchange, and you can trade them at any time throughout each trading day. Each of the shares represents part of an ounce of gold, and so you can trade in gold without actually owning any.
Despite that, it is still advantageous to consider actually buying and collecting gold. As gold increases in value, your collection will also increase in value, and then you can sell off parts of your collection when you want to earn a profit on your investments. As long as you keep your collection safe, your investment is safe. Both of these are considerations that you are going to want to make when choosing investments that are going to work with you, as one may work better than the other.