Me neither, I don't really give a shit either. I'm not on here to trade, borrow etc any way. I'm a HODLER & bitcoin enthusiant/investor. I'm here to learn & discuss bitcoin. Some people are too obsessed with trust etc.
Actually the basics aren't that hard. DefaultTrust is actually
an account that is managed by theymos and that is depth 0. Several people have been chosen in the past and added under DefaultTrust, i.e. now they are depth 1.
This picture should clearly show you who those people are (BadBear, theymos, dooglus, etc.).
Okay so let's say that BadBear trusts used X, and he adds him to his trust list. Since BadBear was depth 1, user X is going to be on depth 2 now; listed under him. If user X adds someone, then they're going to be on depth 3, and so on. Trust ratings left by people on depth 1 and depth 2 are visible by default. Calculating trust scores is something else and I don't feel like getting into that.
A great visualization of the trust network was made by dogie and it could help you understand.