Why can't I export my rigs? I made a series of characters for a game I am working on in Unreal, but when I export them, they don't seem to have their rig anymore. I imported the finished models to find they don't have rigs on them despite how they were exported. Is this a normal thing that happens in Blender, where I can't load in or export rigs? Or is my issue with Unreal, which isn't reading any rigs off the models? 

Also, I am not sure if this has anything to do with this issue, but I exported my models in .obj format.
From the wikipedia wavefront obj page -


  The OBJ file format is a simple data-format that represents 3D geometry alone — namely, the position of each vertex, the UV position of each texture coordinate vertex, vertex normals, and the faces that make each polygon defined as a list of vertices, and texture vertices


If you look in the unreal docs under Managing content they only mention fbx as a format for importing static or skeletal meshes. Blender includes an fbx import/export addon, if you don't see the fbx export option then you will need to enable the addon.

There is also an addon available that eases the blender -> UE process, available on github.