Ban Ki-moon, a South Korean diplomat, is Secretary General of the United Nations. Kalocsay Kálmán was a prominent 20th century Hungarian poet. Looking at these examples, can you tell what the family names are? Unless you’re familiar with Korean and Hungarian customs, you might not know that these cultures usually put the family name before the given name.
To avoid confusion in international communication, Esperanto speakers sometimes spell family names using all capital letters, e.g. Kalocsay Kálmán or Ban Ki-moon. This custom allows everyone to preserve the order to which they’re accustomed, without causing confusion for others. You might want to do the same when writing your first letter to your pen-pal.