An alternate spelling of the noun "folks," first used in 2001 and popularized by tumblr in 2016. Mainstream and academic use is growing after adoption of the term by LGBTQ+ people, especially LGBTQ+ persons of color.
Use of the "X" emphasizes the existence of binary gender systems (especially in indigenous communities) and suggests support of and solidarity with people who are oppressed and/or marginalized.
Increasing protection for the most vulnerable folx in our society increases protection for us all.