Sounds like a dramatic question, but every organisation who is sitting down to plan an event should be asking themselves some form of this question. What is the desired outcome? What is our main objective? Who do we want in the room?
Your event should have a specific purpose that benefits your organisation such as:
Raise your company profile
Bring value to your clients / members
Position yourself as an industry expert
Gain some valuable PR traction
Showcase your product or service
Facilitating networking for attendees
Plus many more. The purpose is individual to you and your organisation, but the question still needs to be asked and once you know the answer to that question, the blueprint for your event will be ready and provide you with a frame of reference for the entire planning process.