Hardware texturing, which you can easily turn on or off, lets you see approximations of the textures, lights and objects in your scene.
What you see depends on your Viewport 2.0 settings and per-object settings. What you see is not necessarily what appears in the final render, but it gives you a good idea.
To see textures, lights, and objects in the viewport
To see the resolution boundaries in the viewport, turn on the Resolution Gate. For more information, see Turn scene view guidelines on or off.