Globalization is defined as the elimination of differences across space and the changes in life that follow as a result. A more nuanced definition is:
"Fundamental changes in the spatial and temporal contours of social existence, according to which the significance of space or territory undergoes shifts in the face of a no less dramatic acceleration in the temporal structure of crucial forms of human activity."
As a concept it is frequently used without understanding the context in which it applies and its effect on social, political, and economic processes. In a political economic context, globalization is not a new phenomenon. Ultimately, globalization reduces the effect of distance on social, political, and economic interactions. This is frequently the result of ongoing technological innovation and is most evidenced by the introduction of steamships and rail transportation during the Industrial Revolution. Advances in technology have reduced barriers of costs of economic transactions across large spans of time and space, thus enabling larger volumes of international interaction in trade, cultural exchange, etc.
Nowadays, popular opinion states that we are in a new era of globalization with recent innovations in communication and the free flow of ideas through the internet, fiber optic cables, and hand-held devices such as smart-phones. It is commonly believed that globalization is an irreversible integration of the world's economies and cultures. However, the reality is that globalization is an evolving process dependent upon government policies, individual decisions, and market forces that does not simply flow unilaterally with technology.That is, globalization has been reversed in the past and there is little evidence to suggest that a reversal is out of the realm of possibility in the modern world. Contrived barriers to globalization, such as linguistic, cultural, and politically imposed barriers may vary over time. These barriers are immune to the ratchet effect of technology, where advancement cannot generally be reversed save for a large scale calamity such as nuclear war or a massive solar flare.
Empirically, we have surpassed the record in volume of international trade, but we have yet to reach the level capital integration in the first wave of globalization.
In regards to international political economy, globalization is significant because it represents the vital link between markets and politics. Globalization can be measured in terms of global movements of trade, capital, and people (or migration). These measurements are imperfect because when aggregated they are unable to differentiate the types of movement, especially in regards to distance travelled, but they do give a general idea of the openness of the world.
Globalization presents new challenges for international institutions. Barton notes that, "Perhaps the biggest single problem for trade today is that the domestic and international institutional mechanisms are no longer fully complementary: the range of domestic stakeholders has expanded, and the international issues have become more complex and demand more domestic institutional change.” 
- Globalization, Stanford Encyclopedia of Philosophy, Accessed 11/19/2010, http://plato.stanford.edu/entries/globalization/
- Barton, et al. The Evolution of the Trade Regime: Politics, Law, and Economics of the GATT and the WTO. Princeton: Princeton University Press, 2006. Ch 1. “Political Analysis of the Trade Regime.”