What is the use of solution manager, and what we can do with solution manager?

Nowadays solution manager is mandatory. 

1. it is used for generating keys and downloading support packages
2. it is used to document user requirements and preparing scenarios what needs to to be adopted using solution manager, where the blue print is the part of solution manager
3. it is used for reporting, solution desk, to manage the change requests and used to monitor the entire landscape 

Central message processing in the SAP Solution Manager:

• Display customer data, problem description, priority, attached documents, Service Level Agreements (SLA)
• Assign processor
• Send messages to the creator and other processors
• Forward message to other processors or support units
• Create documents and URLs
• Attach documents
• Status assignment and monitoring
• Create a worklist with selection conditions