Whats my definition of a true friend

Sometimes, well a lot of times people have problems trying to identify a true friend compared to a fake one. I have had this sooo many times in my life. To me, it's the little things a friend is willing to do for you. For example true friend: someone that calls you when they are upset, fake friend: someone that never opens up to you but always calls you to give you gossip on someone else, good friend: someone that changes their plans if you really need them because your upset, bad friend: someone that doesn't even notice or ask if you upset. This all came to my mind because I have one best friend and you can tell she's a true friend because we have been friends through everything and were always there to help eachother BUT I have another friend that gets on my nerves soo much because of how selfish and rude she is.. She claims were good but yet she doesn't do the simplists things! I would give you a ridiculous example and you would no what I'm talking about.. But I'm kind of scared this person might read my blog! Anyways what do you guys think identifys a true friend? Xo