A "working paper" is a type of publication popular in Economics. Working papers are pre-publication articles, books or reports that are posted publically to support resaerch in a fast moving topic or area but are also usually in the process of being formally submitted to an academic publisher.
As the Shorenstein Center notes, "Working papers can be in various stages of completion. One might be ready for publication in a prestigious journal while another requires significant editing and other changes that could actually alter its main findings" (JR, 2020).
Many economists and public officals use working papers with the understanding that the findings are premininary and subject to change upon final publication. Students may use working papers but should be aware these are NOT peer reviewed articles.