Nation-building is a normative concept that means different things to different people. The latest conceptualization is essentially that nation-building programs are those in which dysfunctional or unstable or "failed states" or economies are given assistance in the development of governmental infrastructure, civil society, dispute resolution mechanisms, as well as economic assistance, in order to increase stability. Nation-building generally assumes that someone or something is doing the building intentionally.
But it is important to look at the evolution of theories of nation-building and at the other concepts which it has both supplanted and included. Many people believe that nation-building is evolutionary rather than revolutionary, that is takes a long time and is a social process that cannot be jump-started from outside. The evolution of the Italian city-states into a nation, the German city-states into the Zollverein customs union and later a nation, the multiple languages and cultural groups in France into the nation of France, the development of China from the warring kingdoms, took a very long time, and were the result, not only of political leadership, but of changes in technology and economic processes (the agricultural and then industrial revolutions), as well as communication, culture and civil society, and many other factors.
I will try as best as I can to explore a little, into the general concept of nation building. Malaysia where I was born and reciding in now, will definitely be interesting enough to be dissected.