Gold and silver are tangible assets, but are often traded in the form of futures or options, which are financial derivatives. Gold, silver, copper, platinum: these are all examples of precious metals that can be obtained as physical assets. Of course, there are also options available so you never have to physically store it in your home. But what's so fun about that? Gold is a unique asset class (read the article on gold as an investment on Wikipedia).
Historically, investments in gold have shown a low correlation with investments in other asset classes, such as stocks or stocks, mutual funds, government and corporate bonds, and even commodities and other precious metals. Since gold has historically shown a low correlation with other types of investment assets, many investors include gold in their portfolios as protection against potential economic downturns. Today, investors buy gold primarily as a hedge against political instability and inflation due to gold's low correlations with other asset classes. The relative independence of gold investments from other asset classes makes investing in gold an attractive strategy for diversifying an investment portfolio.
Gold has certain characteristics that overlap with some of these categories, but in reality gold is a unique asset. So gold isn't a currency, it's not really a commodity, and it's definitely not a cash-generating asset, could gold be a collector's item?.