What does trunking mean with police scanners?

Trunking in the context of police scanners refers to a method of communication used by emergency services that allows multiple radio frequencies to be shared among a large number of users. Instead of each user having a dedicated frequency, trunked systems dynamically assign available frequencies to users as needed, improving efficiency and reducing congestion. Police scanners equipped to decode trunked systems can follow these dynamic frequency changes, allowing users to monitor communications across a variety of agencies and channels.