Software Analysis / Architecture

In the analysis and design stage of software development, the focus gradually shifts from "What to build" to "How to build". 
You must be aware that the Requirement Specifications Document acts as the exit criteria of the Requirement Stage.

Analysis and Design are one of the foremost stages in software development cycle. 
Analysis is the software engineering task that bridges the gap between the software requirements stage and software design. The objective of software analysis is to state precisely what the system will do to provide a solution to the client's need at a functional level. This is captured in the Functional Specification Document.