Registered ports have port numbers ranging from 1024 to 49151. They are loosely bound to some services, and many are not clearly defined. These ports can be used for many purposes, and different programs can determine their use according to their actual needs.
Dynamic or private ports have port numbers ranging from 49152 to 65535. In theory, standard services should not be allocated to these ports. In practice, certain programs, especially Trojan horse programs, prefer these ports as they are often not noticeable and easy to hide.