Disclaimer

What is every country?..

It is not as simple as it sounds. It depends on what constitutes a country
Is it 294? as one site lists including places like the Paracel and Spratly Islands not under the control of any country?

Although those islands are claimed by multiple countries.
The US state department says there are 195 countries but not everybody agrees. The choice of number is political. Is it UN States? in which cases it is 193
Does it include dependent territories such as the Falkland Islands? (these are not usual classified as independent countries in their own right), Greenland is treated by some as a separate country but more correctly it is a territory of the Kingdom of Denmark. Neither will I include as countries.
How about when there is no such UN recognition, such as Kosovo or the PMR? The former with partial recognition, most notably the EU, the latter with none but with its own border guards and currency? Not to forget the Vatican is not a member of the UN.
Taiwan that does not have official recognition by the UN or wide diplomatic representation is treated as a de-facto country. It certainly has operated as such that it would have a strong case international law as such. I for one am in favour of including it.
It is not for me to classify what a country is and it doesn’t matter in that sense if I say (for example) Kosovo is not one if those living within that geographic location consider themselves such, my opinion will have no effect. I have defined a list of every country in the world, and as of this date 30/08/2012, these are the countries in the world that I recognise on the site for practical purposes not to legitimise or de-legitimise any region. Non inclusion or inclusion in the case of controversial countries is not to recognise or deny any parties views on sovereignty or even necessary my own opinions.

I may reveal some political views either intentionally or unintentionally which may cause offence but everyone has internal views that may disagree strongly with others. I consider such things as not the focus of this site. And for now I will make no comment on this site therefore on the status of Israel in whole or part, Nagarno Karabagh, or those, in administrative terms at least, separated from Georgia such as South Ossetia etc.
I arrive at a number of 195 almost in agreement with about.com for practical purposes.

So all the countries are:

Afghanistan, Albania, Algeria, Andorra, Angola, Antigua and Barbuda, Argentina, Armenia, Australia, Austria, Azerbaijan, The Bahamas, Bahrain, Bangladesh, Barbados, Belarus, Belgium, Belize, Benin, Bhutan, Bolivia, Bosnia and Herzegovina, Botswana, Brazil, Brunei, Bulgaria, Burkina Faso, Burundi, Cambodia, Cameroon, Canada, Cape Verde, Central African Republic, Chad, Chile, China, Colombia, Comoros, Congo (Republic of the), Congo (Democratic Republic of the), Costa Rica, Cote d’Ivoire, Croatia, Cuba, Cyprus, Czech Republic, Denmark, Djibouti, Dominica, Dominican Republic, East Timor (Timor-Leste), Ecuador, Egypt, El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Fiji, Finland, France, Gabon, The Gambia, Georgia, Germany,
Ghana, Greece, Grenada, Guatemala, Guinea, Guinea-Bissau, Guyana, Haiti, Honduras, Hungary, Iceland, India, Indonesia, Iran, Iraq, Ireland, Israel, Italy, Jamaica, Japan, Jordan, Kazakhstan, Kenya, Kiribati, Korea (DPRK), Korea (Republic of), Kuwait, Kyrgyzstan, Laos, Latvia, Lebanon, Lesotho, Liberia, Libya,

Liechtenstein, Lithuania, Luxembourg, Macedonia, Madagascar, Malawi, Malaysia, Maldives, Mali, Malta, Marshall Islands, Mauritania, Mauritius, Mexico, Micronesia (Federated States of), Moldova, Monaco, Mongolia, Montenegro, Morocco, Mozambique, Myanmar (Burma), Namibia, Nauru, Nepal, Netherlands, New Zealand, Nicaragua, Niger, Nigeria, Norway, Oman, Pakistan Palau, Panama, Papua New Guinea, Paraguay, Peru, Philippines, Poland, Portugal, Qatar, Romania, Russia, Rwanda, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadine, Samoa, San Marino, Sao Tome and Principe, Saudi Arabia, Senegal, Serbia, Seychelles, Sierra Leone, Singapore, Slovakia, Slovenia, Solomon Islands,Somalia, South Africa, South Sudan, Spain, Sri Lanka, Sudan, Suriname, Swaziland, Sweden, Switzerland, Syria, Taiwan, Tajikistan, Tanzania, Thailand, Togo, Tonga, Trinidad and Tobago, Tunisia, Turkey, Turkmenistan, Tuvalu, Uganda,
Ukraine, United Arab Emirates, United Kingdom, United States of America, Uruguay, Uzbekistan, Vanuatu, Vatican City, Venezuela, Vietnam, Yemen, Zambia, Zimbabwe