Micropenis - "Penis just over half an inch" mainly occurs because of genetic and hormonal problems.
Webbed penis - "concealed penis and trapped penis" These are conditions where the penis is of normal size but outwardly small.
Penile agenesis - this is an ultra rare condition where a child is born without penis. One out of twenty million children suffers from such a condition.
Normal Penis Size - What is the normal penis size?? The most asked and the most difficult question to answer. Numerous stats are available but you can't judge their accuracy because it solely depends on how truthful a man is while revealing his penis size. But yes, as long as your size satisfies your woman, it's not a matter of concern but if not, you need to go for the surgical treatments available.