* if optimistic/unreliable
** mostly ephemeral
Your average wired network is very reliable. Unless something is very wrong, we may trust a LAN to deliver UDP packets. Your average gigabit Ethernet switch will efficiently broadcast or multicast these packets with very low latency and each will arrive at its destination at more or less the same time thanks to "switch fabric". However, the size of UDP packets is effectively limited to 65507 bytes and the size of Ethernet packets is effectively limited to 1500 (~9000 in some cases) bytes. Your operating system (and maybe your hardware) will "fragment" packets larger than 1500 and craft many packets of 1500 bytes or smaller. The remote machines will reassemble these packets and deliver them to the software layer.
This framework does something similar. It chops your data into pieces before delivering them to your operating system for broadcast via UDP. On the remote machines, it receives, collects, and reassembles the pieces to reconstruct your data. You may choose how big the pieces are.
Of course, there are lots of caveats and/or justifications I should add to the statements above (and I will), but for now, just deal with it.