Why is Apfel a masculine noun?
The question showed me a picture of apples, and asked me what the German spelling was. I said "Das Apfel", and it said it should be "Der Apfel" -- I don't understand why?
there is no real answer to why languages pick a certain gender for certain nouns ... in german 'skirt' is masculine --- Der Rock. You just have to remember the gender with the noun -- odd side note, it reminds me of the old Laurie Anderson song with the line "Que es mas macho? lightbulb or pineapple?"
doc9139 is correct, there's often no concrete relationship between a noun and its gender, you must simply learn the gender with the noun. However, there are certain patterns, which this webpage explains http://www.vistawide.com/german/grammar/german_nouns.htm