This is true for simple UDP, but reliable transports are often built over UDP.
As with anything in computing, there are trade-offs between the approaches. One example is QUIC now widespread in browsers.
MoldUDP64 is used by various exchanges (that's NASDAQ's name, others do something close). It's a simple UDP protocol with sequence numbers; works great on quality networks with well-tuned receivers (or FPGAs). This is an old-school blog article about the earlier MoldUDP:
Another is Aeron.io, which is a high-performance messaging system that includes a reliable unicast/multicast transport. There is so much cool stuff in this project and it is useful to study. I saw this deep-dive into the Aeron reliable multicast protocol live and it is quite good, albeit behind a sign-up.
Strictly speaking, you can put any protocol on top of UDP, including a copy of TCP...
But I took parent's question as "should I be using UDP sockets instead of TCP sockets". Once you invent your new protocol instead of UDP or on top of it, you can have any features you want.
Only if you're sending data you don't mind losing and getting out of order
This is true for simple UDP, but reliable transports are often built over UDP.
As with anything in computing, there are trade-offs between the approaches. One example is QUIC now widespread in browsers.
MoldUDP64 is used by various exchanges (that's NASDAQ's name, others do something close). It's a simple UDP protocol with sequence numbers; works great on quality networks with well-tuned receivers (or FPGAs). This is an old-school blog article about the earlier MoldUDP:
https://www.fragmentationneeded.net/2012/01/dispatches-from-...
Another is Aeron.io, which is a high-performance messaging system that includes a reliable unicast/multicast transport. There is so much cool stuff in this project and it is useful to study. I saw this deep-dive into the Aeron reliable multicast protocol live and it is quite good, albeit behind a sign-up.
https://aeron.io/other/handling-data-loss-with-aeron/
Strictly speaking, you can put any protocol on top of UDP, including a copy of TCP...
But I took parent's question as "should I be using UDP sockets instead of TCP sockets". Once you invent your new protocol instead of UDP or on top of it, you can have any features you want.
There is also ENet which is used in a lot of games (that is, battle tested for low latency applications.)
https://enet.bespin.org