Hi,
What BA does depends on what kind of project he is on, what kind of methodology the project is on, what phase the project is, what the organization style... and depends on other details.
In general a BA acts as a Bridge between IT and Business teams. BA proactively interacts with Business and IT teams (PM, Developers, QA, PMO) to discuss any concerns, issues, solutions or to get any clarifications. I would try to put my understanding of BA role in each phase of SDLC.
In Initial Phase - BA may need to do 'Feasibility Study' to identify if the project is worth spending so and so resources and time, BA may have to prepare Project Scope/Vision/as-is,to-be documents as needed
In Analysis Phase - BA gathers high level requirements, conducts JAD sessions to derive on low level requirements and prepares Business Requirement Document. Then he classifies the requirements into functional requirements, non functional requirements and Business Rules. This categorization is called Requirement Modeling.
In Design Phase - BA creates use case narratives to explain different scenarios that may happen for each key process. BA also creates use case diagrams, activity diagrams to explain the system and its process flows. BA constantly interacts with
In Development Phase - BA proactively supports IT team in getting clarifications or information on requirements by consulting Business users.
In Testing Phase - BA may asked to write high level test scripts for key functionalities of the system, or may review the test cases for requirement coverage. BA may prepare UAT test cases (User Acceptance Test) and may coordinate UAT, by helping Business team with manuals, test data, scenarios and helping clarifying any doubts.
In Deployment - BA may coordinate final review of the developed system, checkout and signoff the project.
So depending on project, the phase of the project, organization style and requirements, BA role keeps on changing...BA is there to Analyze problems, define problem to those who provide solution and carry out his support through out for the success of the project.
Any terms if not clear or sounds new, u can google it up or Modern Analyst helps to understand even better with so many experts through out.
Please correct me if I am wrong any where, As I am just a beginner in Business Analysis.
-Thanks,
Raga.