A reserve, often referred to as a backup, is a secondary source of support or supply that can be used when the primary option fails or is unavailable. This concept is commonly applied in various fields, such as finance, where a reserve fund can help cover unexpected expenses, or in technology, where backup systems protect data from loss. In everyday life, having a reserve can mean keeping extra supplies, like food or batteries, on hand for emergencies. This practice ensures that individuals or organizations can maintain operations and avoid disruptions during unforeseen circumstances, enhancing overall resilience and preparedness.