Protectionism

Protectionism refers to government policies that restrict international trade to help domestic industries. Protectionist policies are usually implemented with the goal to improve economic activity within a domestic economy but can also be implemented for safety or quality concerns.

Within Economics

Protectionism is a position partially opposed to Free Market Capitalism. It supports a limited intervention in the economy by the State - being thus opposed to the "Free Market" aspect - whilst still mantaining private property and trade - remaining Capitalism.

Generally, marxist economics adopt positions which could be considered "protectionist" whilst however not adhering to Protectionism per sé.

The extent to which protectionism can be enacted are still debated; most economists consider it a temporary measure akin to austerity which is unsustainable over the long term, only partly because of economic reasons.

It's also up to debate whether protectionism is beneficial to the economy: Austrian School and Chicago School economists (and similar, such as those aligned with Mises) believe that it causes more harm than good; Keynesians, instead, believe the opposite. It has also at time been endorsed by proponents of the Green New Deal and the New Deal itself.

Within Politics

The position of protectionism is mostly promoted by Populists, particularly on the right (though the "Old Left", contrary to the newer "Progressive Left", also advocated it).

In the United States, however, where the "Right" can be considered largely synonymous with Neo-Conservatism and Liberalism, it's still an unpopular policy, with notable exceptions such as Donald Trump.