Friends

I have some very good friends who helped me move some furniture(I'll post it when i get the room all set up) I am so grateful
and I guess it made me think even more --- me because I recently watched a Sienfied moment where they did not know someone well enough to help them move or take them to the airport which makes me wonder about friends.... some we have known for years but don't see each other all that often and yet we know we can count on them like family.and others we see lots more often but would not ask them to do much for us --I wonder when that changes? what makes a nice friend a very good friend?