Sometimes you want a recipe to only exist when a certain mod is loaded, or maybe have something happen when an empty tag actually has some items. This is where resource conditions come into play. Resource Conditions allow you to define things like these in a non-breaking way.
There are 6 basic types, and 3 'modifier' types.
The TrueResourceCondition returns true. That's all it does.
This one returns true if all mods(defined by id) listed in it are loaded(running in the current environment).
Returns true if any mods listed in it are loaded.
Returns true if all tags listed in it have members(not empty).
Returns true if all features listed in it are enabled.
Returns true if the registry has the identifiers listed in it as entries.
Returns true if the resource condition nested inside is false.
Returns true if either condition inside it is true.
Returns true if both conditions are true.