Since you are confused I will let Milton Friedman explain it here:
Or maybe one of the founding fathers put it better:
"Our interest [is] to throw open the doors of commerce and to knock off all its shackles, giving perfect freedom to all persons for the vent of whatever they may choose to bring into our ports, and asking the same in theirs." --Thomas Jefferson: Notes on Virginia Q.XXII, 1782. ME 2:240
"The system of the United States is to use neither prohibitions nor premiums. Commerce there regulates itself freely and asks nothing better. Where a government finds itself under the necessity of undertaking that regulation, it would seem that it should conduct it as an intelligent merchant would; that is to say, invite customers to purchase by facilitating their means of payment, and by adapting goods to their taste. If this idea be just, government here [in France] has two operations to attend to with respect to the commerce of the United States: 1, to do away, or to moderate, as much as possible the prohibitions and monopolies of their materials for payment; 2, to encourage the institution of the principal manufactures, which the necessities or the habits of their new customers call for." --Thomas Jefferson to John Jay, 1788. ME 7:218
"I think all the world would gain by setting commerce at perfect liberty." --Thomas Jefferson to John Adams, 1785. ME 5:48, Papers 8:332