ZDoom-family refers to source ports that are derived from ZDoom. Due to their common ancestry, all ZDoom-family ports have full compatibility with the vanilla Doom map format as well as Boom maps, and most have compatibility with Hexen format maps. As such, they all support some advanced mapping features, such as slopes, deep water, colored lighting and thing bridges (also called invisible bridges).
ZDoom-family ports also have full support for DeHackEd and BEX patches, and most have support for custom skins. More up-to-date variants which closely follow GZDoom, such as LZDoom and Zandronum, support a vast array of new mapping and modding features such as DECORATE and boast compatibility with modern UDMF maps.