Business Analysts collects the requirement from the customer/ Client as per the clients business needs and documents the requirement in the business requirement specification (BRS) and provide the same to Development Team.
Once the requirement gathering is done the next step is to define and document the product requirement and get them approved from the customer. This is done through software requirement specification(SRS).
High Level Design (HLD) It gives the architecture of the software product to be developed and is done by architects and senior developers.
Low Level Design (LLD) It is done by senior developers. IT describe how each and every feature in the product should work and how every component should work.
The outcome from this phase is High Level Document and Low Level Document
This is the phase where we start building the software and start writing the code for the product. The outcome from this phase is source code document and development product.
When the software is ready, it is sent to the Test Team. They either test the software manually or using automated testing tools which is defined in the SDLC. Once the QA make sure that the software is error free its goes to the next stage which is implementation.
The outcome of this phase is the quality product and the testing Artifacts.
Deployment is done by the development/implementation engineers. Once when the customers start using the developed system then the actual problems will come up and needs to be solved from time to time. Maintenance should be done as per service level agreement.