How address formats differ between countries
The order of a street, a house number, a city, and a postal code is not universal. Getting the format wrong for a given country is one of the most common causes of failed geocoding.
Tag
#address-formats
Address parsing ambiguity: apartments, units and PO boxes
A single address string can hide several distinct pieces of meaning, and the same abbreviation can mean different things in different countries. Parsing it correctly is harder than it looks.
Countries with no house numbering system
Not every country organizes addresses around a street name and a house number. Several use entirely different schemes, and geocoding has to accommodate that.