I would say I have 4 types of friends.
I have real true, true friends, the sort that you'd trust with your life, your childrens lives. They mean the world to you. Those friends I know inside out and accept them for their finer qualities, as well as their not so fine. They also get the best and the worst of me. I have 3 friends like this, DP is one of them. I speak to them every day.
Then I have goof friends who I can call on and not be afraid to cry if I need to, and who I expect to do favours for, and am not shy to ask the same of them. I ring them quite often.
I have accqaintences who I have a massive laugh with, who I send cards to, who come round for dinner, who I invite to parties and out clubbing etc but I don't really call them inbetween to see how their life is and chat to them for half an hour.
Then I have the sort of mates who are mates of mates, or people i share musical tastes with that I see out quite a lot that I get on really well with and we always spend the evening together catching up and cracking up etc but then I won't see them again for months and months and months.
A true friend is someone who accepts me for me, warts and all.
For me a true friend is one who before I had kids would lay down my life for. Now I have kids I have to relook at that, but I would say they are always in my heart with me and I love them, unconditionally. Think that's what it's all about for me, he unconditional bit.