When rendering lists in React, you might have seen a warning about "missing key props". But why do keys matter so much?

🔹 What are Keys? – Keys are unique identifiers that help React efficiently update and re-render list items.

🔹 Why Are They Important? – Without keys, React re-renders everything, making updates slower. Keys help React identify what changed, added, or removed.

🔹 Best Practices:

Use a unique ID (like id from a database) as a key.
Avoid using array index unless items never change.

🔹 Example:

{todos.map(todo => (
<li key={todo.id}>{todo.text}</li>
))}