The thrust of the book is that there are three things that can converge to bring about dramatic and perhaps unexpectedly fast changes in our society. These are the context (the situational environment - especially when it's near the balance or 'tipping point'), the idea, and the people involved. His point is that very small changes in any or several of the context, the quality of the idea (which he calls 'stickiness', ie how well the idea sticks), or whether the idea reaches a very small group of key people can trigger a dramatic epidemic of change in society.