stAPT is a vault designed to accrue the staking yield of the Amnis APT validators. At any time, amAPT can be exchanged for stAPT by depositing it into the stAPT vault, which allows users to earn staking yield on their amAPT. Over time, as validators accrue staking yield, an equivalent amount of amAPT is minted and added to the vault, allowing users to redeem their stAPT for a greater amount of amAPT than they deposited. The exhange rate of amAPT per stAPT increases over time as staking rewards are added to the vault. By holding stATP, you hold a % claim on an increasing amount of the vault's amAPT, splitting staking rewards up among stAPT holders proportional to their share of the total stAPT. This is similar to other autocompounding tokens like Aave's aUSDC and Compound's cUSDC.