Collateral
Assets you lock to back a loan or position, forfeited if you can't repay — the trust substitute across all of DeFi.
Collateral is value you pledge to secure a borrowing position: lock ETH to borrow a stablecoin, or post margin to open a leveraged trade. If you fail to maintain the position — repay the loan, hold the ratio — the collateral is liquidated to make the lender whole.
Because DeFi has no identity or legal recourse, collateral does all the work that credit scores and courts do in traditional finance. What counts as good collateral matters enormously: blue-chip assets get generous borrowing limits, while volatile or illiquid tokens get punishing ones (or none), because the protocol must be able to sell them fast in a crash without creating bad debt.