Diary of a Wimpy Kid discussion

Hi All,
I haven't read a book for years and I really want to get back into reading books, I'm not sure but is Diary of a Wimpy Kid a kid's book? Like I don't see adults reading that book. Anyways I would like to know which is the best one in the series also. Does it make a difference if I read any book in the series or should the be read in order? Thank you. loginasum.com