What Is Visioning, or Creating A Vision?
One of the functions of strategic planning is to inspire people in the organization to work towards the creation of a new state of affairs. The vision is a means of describing this desired future, but it works best to inspire and motivate if it's vivid -- in other words, a vision should be a "picture" of the future.
The visioning process is usually the very first step in the strategic planning process. Imagine it as creating a little movie of the future. A future to be worked towards. Once it's created the next step is to summarize it in the form of a mission statement and a role statement.
See Also: What Is A Mission Statement?