AI solution for Interview Question on BFE.dev
19. What does header `Connection:Keep-Alive` do?

The header Connection:Keep-Alive is used in HTTP/1.1 to maintain a persistent connection between the client and server. This persistent connection can help reduce the overhead of establishing a new connection for each request, improving performance by reducing latency and the number of network requests required.

When Connection:Keep-Alive is used, the client can send multiple requests to the server over the same connection, and the server will keep the connection open for a certain period of time (known as the keep-alive timeout) to allow for additional requests. This helps to avoid the latency and overhead of establishing a new connection for each subsequent request, and can lead to significant performance gains.

It's also worth mentioning that HTTP/2 uses multiplexing to further improve performance. This allows multiple requests to be sent over the same connection simultaneously, reducing the overhead of establishing new connections and improving overall performance.