County lists for properties

[Macy Portillo]

I've seen a lot about people finding either flips or wholesales on county provided lists. I'm still not sure exactly what these lists even are or where to find them. What are the specific lists and the reason properties are on them? How can I access them? I've tried to do some research in my county but I think I'm not sure I'm looking in the right places. I'd love to get some information on anyone who has experience with this.