ERC-4626 standardizes an interface for tokenized vaults with a single underlying ERC-20 asset. Users exchange underlying assets for vault shares and later redeem shares for assets under the vault's rules. The specification distinguishes operations by their fixed input: deposit specifies an asset amount, mint specifies a share amount, withdraw specifies assets to receive, and redeem specifies shares to burn. This common vocabulary makes vault integrations more consistent without prescribing the investment strategy used inside the vault.

Suppose a simplified vault holds 1,200 underlying units and has 1,000 shares outstanding. Before fees and rounding, one share corresponds to 1.2 underlying units. A deposit of 120 units would therefore correspond to about 100 shares, not 120. Actual execution can differ because of accounting, fees, limits, and changing state. Preview methods help estimate a particular operation, while conversion methods express other accounting relationships. Applications must use the method appropriate to the user's intended action instead of treating every conversion as an executable quote.

Standard-compliant vaults can still experience strategy losses, illiquidity, administrative intervention, or accounting attacks. Rounding is especially important for small deposits and unusual initial share prices. OpenZeppelin's discussion of inflation attacks explains how donations and share accounting can disadvantage depositors in vulnerable designs. A reader evaluating a vault should inspect the deployed implementation, its protections, and the underlying strategy. The presence of an ERC-4626 interface does not promise a positive return, continuous withdrawals, or a fixed value per share.