Slovakia
The Slovak Republic and the Czech Republic went their separate ways after 1 January 1993, an event sometimes called the Velvet Divorce. Slovakia has remained a close partner with the Czech Republic. Both countries co-operate with Hungary and Poland in the Visegrád Group. Slovakia became a member of NATO on 29 March 2004 and of the European Union on 1 May 2004. On 1 January 2009, Slovakia adopted the Euro as its national currency.
Postage stamps and postal history of Slovakia
After World War I and the dissolution of the Austro-Hungarian Empire, Slovakia and the regions of Bohemia, Moravia, and Carpathian Ruthenia formed the Czechoslovak Republic. From 1918 to 1939, stamps of the Czechoslovak Republic inscribed either "Česko-Slovensko" or "Československo" were used in Slovakia. 
Between 1939 and 1945, the Slovak Republic, a client state of Nazi Germany, issued stamps inscribed "Slovensko".