Capitalism is an economic system that came about by feudal systems in Europe, and the emergence of mercantilism in the world. There are several different subsections of capitalism, and I will attempt to give an overview of some of those.
In general, capitalism is defined by private citizens owning capital. Capital can be assets, private property, and other things of that nature. Private enterprise is the vessel in which capitalism operates in; where private citizens trade between each other freely.
There are different currencies that can be used within capitalism, and they are typically separated by what they're backed by. Back when the United States of America was set up, we had the gold standard. The gold standard said that our paper money is always backed by a specific amount of gold, and can never go above that amount of gold. This was a way to combat inflation, but has since been phased out and replaced by the Federal Reserve, making our money a fiat currency, or unbacked.
Unfortunately, in capitalism, people are often put down and some have unfair advantages. Wealth inequality is a big criticism from communists and socialists, as they claim the unfair advantages lead to families gaining vast amounts of wealth, and refusing to put it into charity.
Wages are a big part of capitalism, as people work and their employers give them a certain amount of money. The money could be either payed in salary, which is a fixed amount every year/month, or it could be hourly, which is a fixed rate every hour. The minimum wage was set up in 1938 in the United States. This forces employers to, as you guess it, pay someone's wage at or above the minimum.
There are several different sects of capitalism as well. The three main ideologies within capitalism are Keynesian, Austrian, and Chicago/Monetarist.
Keynesian economics came out of the Great Depression, and was developed by John Maynard Keynes. He is considered to be one of, if not the, most influential economists ever. This ideology established the Federal Reserve, and is a very complex and different take on econ, compared to the other two. The general theory he put forth was that during recessions and depressions, aggregate demand, or total spending in the economy, is necessary. There is much more room for subsidies and bail outs in this system, and is the principle theory that is put to use in America today
In the Austrian school, there is a very polarizing theory to that of Keynesian. Where Keynesians advocate for total spending in the economy, Austrians advocate for saving. Austrian economics is the predominant economic school of thought in Classical Liberalism, and ideology that the Founding Fathers mostly followed. In Austrian econ, there is no subsidies or bailouts, they just let the free market run it's course. Most Austrian believe in the "invisible hand of the free market".
Monetarist Theory stemmed from Milton Friedman, an economist who was the advisor to Ronald Reagan, and Margret Thatcher. He advocated for a fixed inflation rate, and open markets. It is kind of a middle ground between Austrian and Keynesian.