Subject: How is gravity related to mass and does gravity always exist?

I understand that the more massive an object, the larger the gravity, 
(such as those observed with planets), however I cannot grasp the concept 
of how two apples hanging from a string can have gravity between them or 
how the gravity exist. After reading through most of the topics, they seem 
to suggest that the gravity between the two apples are negligible, but I'm 
curious to know how gravity exist.

Re: How is gravity related to mass and does gravity always exist?