The "Overton Window" refers to the range of acceptable ideas in politics that an individual can advocate for without the fear of political exile or banishment from one of the major parties. More formally, “a term… meaning the acceptable range of political thought in a culture at a given moment… [which] can be moved. [1]”
Coined by the late free-market advocate Joseph Overton, the concept has taken off since its formalization in 2003 as a useful way to discuss what a politician can and cannot say. For example, advocating for slavery or nazism would clearly be outside of the window, beyond what most constituents are willing to entertain, and anyone who argued for them would find themselves without a party.
Up until recently the scope of the Overton Window was controlled in equal measure by the major political parties and the media. If neither party's leadership would tolerate an idea, for example marijuana legalization for most of the last 50 years, anyone arguing for said idea would not be welcome into either party. So to it went with the media, if the major news outlets were not willing to cover a person or topic seriously than the person or topic was not viewed as serious.
However, in recent years, the rise of social media coupled with political reforms have eroded the control these classic stakeholders have over the Overton Window. Individuals sharing ideas that were once unacceptable or fringe are now able to take their messaging directly to the public and reframe the public conversation in new and unexpected ways. Also, the decrease in the power of parties to prevent candidates from running under their banner (mostly due to democratization efforts in primaries and the decentralization of fundraising) has allowed aspiring politicians to push the boundaries of what is acceptable in so long as they win their races.
"The success of Donald Trump’s campaign is perhaps one of the most notable examples of how social media has “fundamentally rewire[d] human society” by destabilizing and replacing traditional political and social norms. Social networks have allowed people to communicate more freely, “helping to create surprisingly influential social organizations among once-marginalized groups.” These groups in the past likely would have been ignored because of the perceived dominance of the existing status quo, but social media has allowed for formerly overlooked concerns to gain traction [2]."
"By transforming the far right’s racial subtext on immigration into … let’s call it “super-text,” Trump revealed that the Overton window was far wider than establishment politicians and the media had previously assumed. The dynamic played out on the left, as well, with Bernie Sanders’ unexpectedly strong showing in the 2016 Democratic primaries revealing that for a large chunk of America’s liberals, “socialist” was no longer a dirty word. Whatever the reason, the electorate was amenable to ideas that just four years earlier would have been anathema. [3]"
As platforms like Parler, Rumble, Gettr, and Truth Social grow and their bases radicalize each other, it is likely we will see the Overton Window continue to expand. Each time someone is banned from other major platforms like Twitter or Facebook, we see them migrate over to these alternative sites and bring large chunks of their users with them. Once away from the moderators and fact checkers who "censor" them, these individuals have the freedom to become more and more radical which their followers in turn come to see as normal.