The simple definition of investing is the act of using money to purchase an asset that is expected to generate a profit later.
The modern investment structure dates back to the 1600s with the Amsterdam Stock Exchange founded in 1602. Capitalism has long relied on investors to fund growth and innovation.
Investing begins with sellers, selling a piece of the company for a certain price to a given investor (the buyer). For every seller, there has to be a buyer. Most transactions are electronic and recorded on a ledger that is managed by a brokerage or a private institution.
It's basically anything you want to invest in. Everything from stocks, retirement accounts, bonds, real estate, commodities, cryptocurrency, NFTs, businesses, and more.
You can invest via online brokers like TD Ameritrade, Charles Schwab, M1Finance, or via crowdfunding like CrowdStreet. You'll find art investors and wine investors along with many through a quick google search.