How do digital radios tune?

[Tech2025]

I get how analog ones with knobs tune by physically changing length of elements to match the frequency, but what about the ones that just have a screen and you type in what frequency you want?

 

[berkeman]

By using a very cool circuit called a "frequency synthesizer":

https://en.wikipedia.org/wiki/Frequency_synthesizer

 

[sophiecentaur]

physically changing length of elements

Even the old 'steam radios' can work without moving parts. You can achieve the function of a variable Capacitor (the only moving part that was necessary in most radios) with a semiconductor diode.