Whether a surety remains bound when the underlying debt is void, varied or released turns entirely on which type of obligation was given. This chapter starts by drawing the distinction between guarantees and indemnities, then covers the formation requirements — including the Statute of Frauds writing rule — and the co-extensive liability principle that lets a guarantor raise the debtor's defences. It moves through the ways a creditor's own conduct can discharge a guarantee, from material variation and release of the debtor to giving time or impairing security, and the duties on a bank put on inquiry for undue influence. It closes with enforcement, the paying guarantor's rights of subrogation and contribution, and the distinct world of demand guarantees and performance bonds, where the autonomy principle means payment follows the demand unless fraud is shown.
