Direct3D is a API for rendering 3D graphics. The current version to care about is DirectX 11 and DirectX 12. These pages is about DirectX11. Direct3D is part of DirectX and is available on Microsoft windows and Xbox platforms (Xbox, Xbox 360 and Xbox One).
There are three objects in DirectX that are used frequently. They are Device, DeviceContext and SwapChain. The class of each depends on the the directx version. For the first two in DX11 they are prefaced with ID3D11 and the last one with IDXGI as it is part of the
Microsoft DirectX Graphics Infrastructure.
Device: Used to create GPU resources such shaders, textures, buffers and state objects.
DeviceContext: Used to configure the rendering pipeline and draw things.
SwapChain: Stores the buffers one is rendering to and show them to the screen when rendering is complete.
DirectX10 Tutorials - 2011
Optimizations and New DirectX Features in Just Cause 3 - 2016
DirectXMesh - 2014
Avoiding Catastrophic Performance Loss Detecting CPU - GPU Sync Points - 2014
DirectX 11 C++ Game Camera - 2013
An FPS Camera in SlimDX - 2013
Rendering to a texture - 2011
DirectX11 hints - 2010
Texture Modification using Render Targets, with some Stencil Buffer Action - 2010
Designing a Flexible Vertex Element System for XNA Using Attributes - 2008
Experiments with DirectX Raytracing in Remedy’s Northlight Engine
DirectX 10 Performance - 2008
DirectX10: porting,performance and “gotchas” - 2012