Computer architecture is the abstract description and specification of why, what, and how various hardware and software components are combined to create a computing device. This tag should be used with questions about the relationship between components making up a computer, what components are included or excluded in a computer, how components are connected, what data flows over the connections, and why components and connections are good choices.
Computer architecture is an area of study, research, and engineering of how hardware and software components can be selected, connected together, and operated to perform computations. Computer architecture is variously described as "a set of rules and methods that describe the functionality, organization, and implementation of computer systems" (Wikipedia topic Computer architecture) or as "a specification detailing how a set of software and hardware technology standards interact to form a computer system or platform" (Techopedia topic Computer architecture) or as "software standards, hardware instructions and technology infrastructure that defines how computer systems, platforms and programs operate" (Best Choices Schools What is Computer Architecture).
Questions using this tag would typically involve questions about computer design:
the hardware components of a computer and why those components are chosen
how hardware components are electrically connected and why connected in those ways
how the software of a computer is organized and the relationships between software and hardware
technology changes and how those changes influence computer design