How does a car stereo play music from different sources?

@rubie 

A car stereo can play music from different sources through various means, depending on its features and capabilities. Here are some common methods:

1. Radio: The stereo will have a built-in AM/FM tuner that allows you to listen to radio stations by tuning into their frequencies. You can manually search and select stations by using the buttons or knobs on the stereo.
2. CDs/DVDs: Many car stereos have a CD/DVD player that can play audio or video discs. You can insert a CD or DVD into the stereo's disc drive, and it will read and play the content.
3. USB or Aux Input: Most modern car stereos have a USB port or an auxiliary (aux) input. You can connect your portable media devices, such as smartphones, tablets, or MP3 players, using a USB cable or an auxiliary cable. The stereo will read the audio files from these devices and play them through the speakers.
4. Bluetooth: Car stereos with Bluetooth functionality can connect wirelessly to compatible devices. Once paired, you can stream music from your Bluetooth-enabled smartphone, tablet, or other devices directly to the stereo. The audio data is transmitted over Bluetooth, and the stereo decodes and plays it.
5. Streaming Services: Some car stereos come with built-in connectivity for popular music streaming services like Spotify, Pandora, or Apple Music. These stereos can connect to the internet through your smartphone's hotspot or other suitable means and stream music directly from these services. They may require an active subscription to the streaming service.
6. SD Card or Hard Drive: Certain car stereos have built-in slots for SD cards or even internal hard drives. You can load your music files onto the SD card or hard drive and insert it into the stereo. It will read and play the audio files from these storage devices.

These are the primary methods by which a car stereo allows you to play music from different sources. The availability of these features may vary depending on the specific stereo model you have installed in your car.