Always provide meaningful keys for React components and fragments to ensure proper rendering and re-rendering behavior. Use composite keys when component identity depends on multiple values, and include keys even for Fragment components when rendering lists. For components that need to re-render based on multiple state changes, create composite keys: ```jsx ``` For Fragment components in lists, always include a key prop: ```jsx {PROVIDERS.map(({ value, label }, i) => ( {label} ))} ``` This prevents React from incorrectly reusing components and ensures predictable rendering behavior, especially when component state or props change frequently.