To "realize" means literally "to make real." It is an act of creation. In the case of large-scale change, to "realize" involves many, many acts of creation.
And who does all of this creating? Everyone in the organization is involved in making a change happen. And everyone will get involved, either by leading the change, getting involved and positively engaged, or in some cases, by negatively reacting to what's coming. To leverage and move these forces positively in your enterprise, you must first understand how these forces work.
Communication and conversation are the starting points for informing people and bringing about awareness of a change that's coming. Through dialogue and activities like planning, people become participants in the change. Engagement leads to buy-in and commitment to the vision for the change. As people become committed in this process, they continue the cycle by communicating to others, and the community of people committed to realizing the change continues to grow.
These are just 3 paragraphs from a Suzanne Zeman's White Paper on Realizing Change. Filled with examples, tips and resources, the complete paper is available free by sending your request to her via email or a phone call.