This piece is part of the Radical issue, a special package from Outward, Slate’s home for coverage of LGBTQ life, thought, and culture. Read more here.

When we celebrate queer history, we’re usually thinking about the elders who came before us and the sacrifices that they made to ensure that future generations wouldn’t have to go through the same hardships that they did. By remembering their radical calls for acceptance and civil rights, we’re really thinking about action-oriented activism. But in doing so, we leave out the importance of the practice of kink and BDSM, which are radical acts in their own right. It’s time to correct this, to include and center kink as a valid part of queer history—because without it, we are erasing an essential part of our heritage.

Kink has been somewhat mainstreamed in recent years by films, books, and popular media (ahem, Fifty Shades) that speak to only one part of what it means to be in the lifestyle. But what exactly makes kink radical? There’s a taboo around discussing sex and sexuality in our culture still, and it is especially seen as taboo for queer people, who have been ostracized and outcast for not falling into heteronormative expectations of how we should love and form relationships. Many kink and BDSM (an acronym standing for bondage, discipline, sadism, and masochism) subcultures were formed in response to individuals’ desire to fight against these expectations. These were often some of the few spaces where queer people, before civil rights efforts had gained any ground, could form relationships that existed outside of shame and build their own communities.

Offering this kind of safe space for exploration is one of kink’s great virtues, as it provides another option for relationship building and sexual expression that doesn’t subscribe to traditional notions of how these structures should exist. Kink includes rather than excludes, because it is built on the foundation of embracing what can otherwise be shunned and misunderstood. In this formation-in-rejection, kink and LGBTQ community members have much in common.

One of those commonalities is the freedom to develop new and unique ways of relating. Within kinky subcultures, participants have to create their own traditions, practices, and even language to connect and express who they are and how they feel. The practice of flagging is a prime example of this. Flagging is the practice of using handkerchiefs within the queer and kink communities to indicate interests and fetishes, with different colors indicating different identities (top, bottom, switch) and acts, like bondage and S&M.

For those outside of the community, these colors would simply be interpreted as fashion. But flagging’s covertness allows this form of identification—with queer individuals in the lifestyle being able to find each other without doubly outing themselves—to exist even in nonkink spaces. This kind of passing is vital for the queer kink community to continue to exist, even where any outward display would be frowned upon.

Flagging is a radical act because it centers queer resistance, even in spaces where being openly out isn’t an option. A central theme that runs through queer history is the stigma asserting that queer sexuality is “wrong”, “dirty,” and something to demonize. Yet flagging is a practice that has historically helped so many in the community to turn such stigmas on their head. Queer sexuality is an important part of our identities, and by acknowledging how important kink has been for queer history, we can begin to see the ways that flagging and kink can connect us within the community to the power we have and remind us of how far we’ve come.

Engaging in kink as a queer person today is part of that practice. It is a celebration of our sexuality, but it also connects us to a community that is larger than us. Queer and kinky communities can continue to thrive and live on, even as they adapt to better fit the social temperature of the time, in order to preserve the community’s history and future. And in doing so, we allow for this part of our history to carry forward, as it should.

Read all of Outward’s special issue on Radicalism. And queer your ears with a special radical-themed episode of the Outward podcast.