What is the difference between a city and a town?
In the United States, an incorporated city is a legally defined government entity, with powers delegated by the state and county and created and approved by the voters of the city. It can provide local government services to its citizens.
In most places in the U.S. a town, village, community, or neighborhood is simply an unincorporated community with no governmental powers. Usually, county governments provide services to these unincorporated communities. Some states do have official designations of "towns" that include limited powers.

Generally in the urban heirarchy, villages are smaller than towns and towns are smaller than cities but each country has its own definition of a city and an urban area.

What is the most common surname in the world and U.S.?
The most common surname (last name) in the world is Chang.
In the United States, the most common surname is Smith (followed by Johnson, Williams, Jones, and then Brown).

What is the most popular language in the world?
Over one billion people in China and nearby countries speak Mandarin, which is often called Chinese.
Hindi, English, Spanish and Russian round out the top five.

What is the most popular religion in the world?
With over 1.1 billion adherents, Islam is the world's most popular single religion.
Following Islam, Catholicism, Hinduism, Protestantism, and Buddhism round out the top five.

However, there are almost 2 billion Christians in the world - divided into several subsets of Christianity.

Almost one billion people (one-sixth the world's population) are agnostic, atheists, or indifferent to religion.

What's the difference between a capital and a capitol?
The word capitol is used to refer to the building where a legislature (such as the U.S. Senate and House of Representatives) meets while the word capital refers to the city which serves as the seat of government.
You can remember the difference by thinking of the "o" in the word capitol as a dome, like the dome of the U.S. Capitol in the capital Washington D.C.

What's the difference between a nation and a country?
While the terms country (synonomyous with "State") and nation are often used interchangeably, there is a difference. A country is a self-governing political entity while a nation is a tightly-knit group of people which share a common culture.

Which countries are doubly landlocked?
A landlocked country is a country that has no access to the ocean at its borders. A doubly landlocked country is one which is surrounded by landlocked countries. The two doubly landlocked countries are Uzbekistan and Liechtenstein.
Uzbekistan is surrounded by the landlocked countries of Kazakhstan, Kyrgyzstan, Tajikistan, Afghanistan, and Turkmenistan.

Liechtenstein is surrounded by the landlocked countries of Switzerland and Austria.

Which countries border only one other country?
While most island nations have no neighbors at all, there are ten non-island countries that share a border with only one country.
The ten countries are: Canada (which borders the U.S.A.), Monaco (which borders France), San Marino (which is surrounded by Italy), the Vatican City (which is surrounded by Italy), Qatar (which borders Saudi Arabia), Portugal (which borders Spain), Denmark (which borders Germany), Lesotho (which is surrounded by South Africa), and South Korea (which borders North Korea).

What proportion of humans who have ever lived are alive today?
At some point over the last few decades, someone started a notion to alarm people that population growth was out of control. Whoever it was said that a majority of the humans who have ever lived were alive today. Well, that's a gross overestimate.
Most studies place the total number of human beings to have ever lived at 60 billion to 120 billion and since the world population right now is a mere 6 billion, the percent of humans who have ever lived and are alive today is anywhere from a mere 5 to 10 percent.

Who are the members of NATO?
There are nineteen member countries of NATO, the North Atlantic Treaty Organization. They are: Belgium, Canada, Czech Republic, Denmark, France, Germany, Greece, Hungary, Iceland, Italy, Luxembourg, Netherlands, Norway, Poland, Portugal, Spain, Turkey, United Kingdom, and United States.

Who are the members of OPEC?
There are eleven member countries of OPEC, the Organization of Petroleum Exporting Countries. They are: Algeria, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, and Venezuela.