What is trust?

Trust. Can't seem to understand how to trust. Trust is just something u tell others to do when u can't explain and don't wanna admit that u have lied to them. To tell the truth, I'll never ever trust anyone 100%. That's sumthing I used to do a long time ago, and bad experiences have made me trust ppl less and less.
What I believe is that the more u trust sumwan, the more hurt u will get when u find out that sumwan betrayed ur trust. I can't trust my emotions 100%, y should I trust others? I wonder what it is to feel like having sumwan u know u can trust completely. It must be relaxing just putting ur whole heart into it, without having to worry. When can I learn to 'trust' like that, and more importantly is there anyone that I can trust right now?