This is a visualization of an HTTP image request, slowed down 40 times. You can clearly see the handshake, slow-start ramp-up and full bandwidth phases.
Created using Packet Flight: http://github.com/aristus/packet-flight
Each flying circle represents a network packet. The small green ones are control packets: ACK, SYN, etc. The larger blue ones are data packets.
The data is from a real tcpdump of a 300KB image download.