General perspective projection matrix

Hi, I am very confused with this projection matrix shown in the diagram above. For pinhole camera, I have learnt the projection matrix to be of [[f, 0,0], [0,f,0], [0,0,0]]. How was this derived from the general matrix in above diagram?

I have also not heard about clip space and ndc coordinates earlier. My lnowledge earlier was that perspective projection transforms 3d (camera coordinates) to 2d (image coordinates). What are these clip space and ndc coordinates in between? Why are …

clip computervision general matrix perspective projection space