API,
API or Application Programming Interface is a bunch of tools for building software applications> A good API is when the software allows the user to create software with ease by supplying the necessary building blocks. Then the user will put these blocks together. API's are open to the public to use for free.
Direct3D
Direct3D is an API for microsoft windows. Direct3D is used to render 3D graphics in applications where performance is important, such as games.
OpenGL
OpenGL, or also known as Open Graphics Library, is a cross-language, cross-platform API for rendering 2D and 3D vector graphics. The API is typically used with a Graphics Card to gain hardware-accelerated rendering.
Graphics Pipeline,
Graphics Pipeline is the process of making a 3D image or model look like a 2D raster image. It does this by flattening the image to a 2D form.
https://msdn.microsoft.com/en-us/library/windows/desktop/ff476882(v=vs.85).aspx
The image above shows you the rendering process.
Rendering,
Rendering is a process where your computer is creating a 3D or 2D Image. One thing that is rendered is 3D models, which are used within Video Games, depending on how complex your model is determines the speed of the rendering time. Rendering is the final process were you can create a 2D image which can be opened using another software e.g. Photoshop.
Rendering,
Rendering is a process where your computer is creating a 3D or 2D Image. One thing that is rendered is 3D models, which are used within Video Games, depending on how complex your model is determines the speed of the rendering time. Rendering is the final process were you can create a 2D image which can be opened using another software e.g. Photoshop.