Most scanners these days have Search functions. These can be “Service Search”, “Range Search” and some sort of near-field search. Each works differently but provides a similar result: New stuff to listen to.
Service Search allows you to root out users of specific services, like aircraft, marine, railroads etc. Select the service you want from your scanner’s controls and the radio will go thru frequencies used by that service and stop on active traffic. Like to listen to planes, trains or boats but don’t know what channels they use in your area? Use Service Search and find out.
Range Search allows you to set up a pair of frequencies (or several pairs on some radios) and search from one end to the other over and over, stopping on active frequencies. This is handy if you know about where they operate or want to search out and find new stuff in a specific frequency range.
Near Field reception (called CloseCall by Uniden, Spectrum Sweeper on GRE and Whistler radios etc.) is a fascinating way to find operations where you least expect it. CloseCall and it’s brethren allows you to find a nearby transmission so you can listen to very local operations. While it works a little differently behind the scenes, the results are very similar with GRE/RadioShack and Whistler radios.
On a mobile scanner in a vehicle using an outside antenna you may well hear base station traffic within a few miles or so and mobile radios within a few blocks. Using a handheld scanner your range will be less but then likely you will want to hear stuff closer to you anyway.
Next time you are at the mall take your handheld scanner with a set of earbuds and walk around a bit. You will be amazed at the amount of radio traffic you can hear. The largest department stores to the little boutiques all use radios these days. It isn’t just the security and maintenance guys either.
Some radios also let you store hits from the various Searches. Then you can go back and review them to figure out who or what they are.