how can an application use port 80/HTTP without conflicting with browsers?

Question

If I understand right, applications sometimes use HTTP to send messages, since using other ports is liable to cause firewall problems. But how does that work without conflic

Answer 1

Clients usually pick a port between 1024 and 65535. It depends on the operating system how to handle this. I think Windows Clients increment the value for each new connection, Unix Clients pick a random port no.

Some services rely on a static client port like NTP (123 UDP)