There was a specific feature in the .Net Framework version of EF called “database first” that would analyze your existing database and generate an xml file describing it that EF would use to generate models on the fly. It was pretty horrible and thankfully isn’t supported by modern EF Core. However the term database first stuck and it’s really come to refer to any any scenario where you manage your database using a tool other than Entity Framework migrations. Could be a dedicated migration tool, Sql Server database project, whatever. Then you either create EF models to match the tables or use a tool to generate them.