Models only visible from one side

I’ve only just started using blender so hopefully this wasn’t better suited for the modeling section, but while I was following a tutorial I was modeling a jacket and realized that the model was only visible from the outside. This means if the jacket was flipped inside out it would be completely invisible, and since I am modeling a collar on it I can only see the collar from one side. Is there a way to prevent this? Also on a less important note, is it possible to make it so the object I have selected is darker that the others both in solid and wire frame view so I can distinguish say the jacket vertices from the ones on the body? Thanks!

Regarding one-sided visibility: backface culling is in effect. This can be caused by:

  • Enabling Backface Culling in the N Panel (Display pane)
  • Enabling Textured Solid mode in the N Panel (Display pane)
  • Working in Textured viewport mode

Note that simply disabling Backface Culling won’t help if one (or both) of the last two options are true as well.

If you want to keep your collar non-manifold (i.e. not give it any thickness) you’ll have to manually flip the normals on the “inside” faces that are wrapped onto “outside” (in Edit mode select those faces, W -> Flip Normals). This way even with backface culling active you’ll still see those faces.
However, it’s a good idea to give your models at least an illusion of thickness by modeling it on the visible parts. For example, you could make a collar like this:

On the left is a simplistic “collar” one-polygon thick, while on the right it’s the same collar with some “thickness” added. This helps to keep normals consistent throughout the mesh and to make your mesh visually more convincing.

Regarding making active object darker: you can achieve this in solid view by assigning a darker material to the object. There is no way of doing this for wireframe view, however.

Thank you so much! I had texture solid enabled, and I never would have figured that out by myself. Also the additional information is really helpful, and I’ll keep it all in mind while moving forward.