A reserve, often referred to as a backup, is an additional resource or support that can be used when the primary option is unavailable or fails. This can apply to various contexts, such as data storage, where a backup copy of files is kept to prevent loss in case of hardware failure or accidental deletion. In finance, a reserve may refer to funds set aside for unexpected expenses or emergencies. Organizations often maintain reserves to ensure they can continue operations during challenging times, providing a safety net that helps manage risks and uncertainties.