Most definitely.
I've known my best friend for 21 years. In those 21 years we have become the kind of friends wherein nothing is held back, or saved for later, or unsaid. She is the only person who knows pretty much everything about me. Even the ugly/sad/petty/unspeakable stuff you normally don't tell anybody at all, because you don't want to be judged. The stuff that runs through your mind late at night before you fall asleep? I tell her all that, too. And it's a two-way street. Our pact is that no matter what she says, or what I say, there is no judgement. Just support. Just an open mind. An open heart. A sounding board. Whatever you want to call it. In other words, she is my safety zone, and I am hers. I trust her implicitly.
I wish I had that with my mother, but she was a very traditional parent who to this day treats me like a child. (I am 40... lol) My siblings are all 14+ years older than me, and while I love each and every one of them we aren't really close.