I can imagine the consternation of a well informed student attempting to answer that question for a class. One hundred years ago, he could have answered "capitalism" and been about 99% correct.
Today, what we have here is an unholy mixture - a small bit of capitalism, a heaping spoonful of socialism, and a liberal dousing of corporatism.
Capitalism is a politico-economic system in which property and specifically the means of any production are privately owned, and men deal with one another as traders - trading value for value.
Socialism places property under the (in name) ownership of the entire public, and production and value are distributed (by a few) in an equitable manner "to all" as determined by 'the few.'
Corporatism can exist in various forms along with socialism or capitalism, but is generally a deviant form of capitalism in which the government (which is supposed to be protecting the individual rights of the individual people) is in bed with various corporations (to the corporations' market advantage). IE the corporations by political "pull" with the government, use the force of the government to gain forcible advantage (or total control) in their market.
So, what we have here, is an ugly, smelly mixture. We take the one moral and effective system, capitalism, and create all manner of evil by enslaving individuals to the group "for the public good" - socialism. Then, since there is really no such thing as "the people" - just individuals - we naturally get not competition among private companies but rather competition among political pressure groups and between companies and even nations competing through political /legislative/regulatory pull within our own government. Competing for what? The summed productive value (eventually in terms of money) of all American individuals. A healthy chunk (taxes) of all production is confiscated from all the actual producers, then political groups war over dividing up that stolen pie and corporate powers buy and pressure government favor so as to be paid some of that pie by the government or be positioned via the power of the govt regulatory functions to obtain unfair market advantage so as to soak up (unfairly) the production of the nation that was left over after taxes. And thus we are enslaved to corporations (those which are in bed with the govt.)
And that's how we get what we have here.... A disintegrating realm of freedom, chiseled away on one side by enslavement to "the group - the public," and cut and mangled on the other side by forced enslavement to politically powerful corporate interests eager to loot some of that "public" money.
Be aware - those advocating socialism have and will continue to claim that corporatism IS capitalism or is inherent in capitalism. This isn't the case, but it's one of the reasons many well meaning people are confused about capitalism.
Here used to be a place of freedom and thus hope, and now, after just 80 or so years of misguided political and economic ideology, here is a place of decay, enslavement, unfathomable debt, disillusionment, confusion, corruption, and despair.
And this horrible horrible journey was all due to, at bottom, one single wrong idea.
God has ordained it, reason and an objective view of the nature of man confirms it, and the very nature of cause and effect will not disobey.
A man's life may not be made a means for another.
You can not build a friendship on the contrary view. You can not build a family. You can not build a nation.
And yet our media and nearly all in Washington go on, day after day, trying to make that simple truth untrue. If we just moderate our policies (based on that idea) a bit - compromise - THEN it'll work. No. 'We haven't gone far enough - if we just go ALL out and make EVERYONE a means for everyone else - THEN it'll work!' No.
The cloud of preconceptions, pressing crises of the moment, and a national ideological landscape smeared with the detritus of Kant and misunderstood religiosity make the application of such fundamentals entirely opaque to them.
This is what we have here..