Why go
The characters 日本 link the country’s name to the sun’s origin, viewed from the Asian mainland to the west. Their different readings survive in everyday language and formal names. Notice how Tokyo’s Nihonbashi and Osaka’s Nipponbashi use the same characters, then check the city before following an address.
The full story
Nihon and Nippon are both established readings of 日本. The first character means sun or day; the second means origin or base. This combination explains the familiar description of Japan as the Land of the Rising Sun. It reflects geography as seen from the Asian mainland rather than a special place where visitors can watch sunrise. Nippon often appears in formal names, on money and in sporting contexts. Nihon is common in everyday compounds, including Nihongo, the Japanese language. Usage depends on the particular name, so a single rule will not predict every pronunciation. The English name followed a different path through other languages. Marco Polo’s account used Cipangu for an island he had not visited, and related forms later circulated through European and Asian trade. Earlier names such as Wa and Yamato also belong to different historical contexts. For a traveler, the useful point is simple: different names can refer to the same country, while similar place names can identify very different destinations.