What is Computer Architecture?

Computer architecture is the arrangement of the various computer functional units together in order to make out the instructions carry out in a smooth, accurate and efficient manner. It also deals with the inter-communication between the various functional modules so as to maintain flow in the processing of the instruction. This includes the information formats, the instruction set, and techniques for addressing memory.
This definition arises to important questions, listed below:
What are these functional components are?
How do they communicate?