how many countries are there?

Answer 1

According to the United Nations, there are 192 individual countries. However, for an extensive list and breakdown, have a look at wikipedia or about.com.

Answer 2

"Following is the alphabetical list of the 192 Member States of the United Nations with, between parentheses, the date on which they joined the Organization." [1]

"As of 2007, there are 192 United Nations (UN) member states. Each member state is a member of the United Nations General Assembly.
According to the UN Charter, Chapter 2, Article 4... In principle, only sovereign states can become UN members, and today all UN members are fully sovereign states. However, four of the original members (Belarus, India, the Philippines, and Ukraine) were not independent at the time of their admission. Moreover... some entities which can be considered sovereign states according to the Montevideo Convention are not members due to the fact that the UN does not consider them to be sovereign states, the lack of international recognition or opposition from certain members.
Other intergovernmental or legal entities can only be General Assembly observers, allowing them to speak, but not vote in Assembly meetings.
In addition to the member states discussed above, there is one non-member observer state, the Holy See (which holds sovereignty over the state of Vatican City). It has been a permanent observer since 6 April 1964. Non-member observer states are recognized as sovereign entities, and are free to submit a petition to join the General Assembly at their discretion. For example, Switzerland was also a permanent observer state from 1948 to 2002, but became a full member on 10 September 2002 after a national referendum.
The Palestine Liberation Organization (PLO) was granted observer status by General Assembly resolution 3237 on 22 November 1974. After the proclaimed declaration of the State of Palestine by the PLO, its designation in the UN was changed to Palestine by General Assembly resolution A/RES/43/177 on 15 December 1988. Palestine's status in the UN is "a non-member entity".
The sovereignty status of Western Sahara is in dispute between Morocco and the Polisario Front. Most of the territory is administered by Morocco, the remainder (the Free Zone) by the Sahrawi Arab Democratic Republic (SADR), proclaimed by the Polisario Front. The SADR is a full member of the African Union, but is neither a member nor observer of the UN. Currently, 43 UN member states maintain diplomatic relations with the SADR.
The associated states of New Zealand, the Cook Islands and Niue, while self-governing in their domestic affairs, have their foreign affairs represented by New Zealand, and therefore do not have UN membership.
Some international organizations, non-governmental organizations, or entities whose statehood or sovereignty has not been precisely defined, such as the European Union, the International Committee of the Red Cross, and the Sovereign Military Order of Malta, are also UN observers." [2]

Answer 3

not an easy question as some are official some are not.
its somewhere in the region of over 250