There are two significant subsections in this step.
1) Analysis of the data available at the beginning of the project.
This might be done in-house by a specialist within an organisation requesting web system. Or, this could be done in the process of creating paperwork for an invitation to tender for particular web solution. In a different scenario (with no tender), this could be put together by your chosen provider.
2) The system architecture is initially created based on your internal operations.
We may have complex systems that are not used efficiently due to insufficient manpower to process data. Business settings may also limit the functionality of system or require extra elements to be developed that would not be otherwise created. It is an important money saving and business optimisation step in the process of web system implementation.