Unfortunately, not all passports are created equal.
There are times when those of us in the United States, Europe and elsewhere take for granted all of the privlidges we possess. One of these privlidges is the ability to travel to many foreign nations with great ease. For example, as a United States citizen, I am able to travel to 172 different countries. In my lifetime, I hope to venture to every single one. However, there are still many places that are still extrememly difficult to visit right now. These places may only (currently) be accessed by using a government sanctioned tour. Cuba and Tibet are two at the top of my list. North Korea, Bhutan, and Turkmenistan are also unavailable without a government sanctioned tour (shockingly, Iran is a place that is no more difficult to visit than many other countries).
Citizens of certain countries, however, do not enjoy the same travel freedoms that United States and most European citizens do. For example, Afghanistan has the least powerful passport. Citizens of Afghanistan are only allowed to travel to 28 countries, and Iraq is not far behind at 31. Citizens of Morocco may only visit 51 nations, while India & the Dominican Republic may only travel to 52. Even Monaco falls behind the United States at 148 nations available for it's citizens to travel to. Check out this infographic created by Ricky Linn to see how powerful your passport is.