What are fuses used for?

I have, I’m sure to many, a very dumb question. I keep reading about fuses.  I have a fairly sophisticated system and have never come across the need for a fuse.
Can someone tell me where these fuses go and what they’re used for?
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Who said anything about two years?
Three guesses. The first two don’t count.
I highly recommend a fuse selector/switch to facilitate a convenient change for different genres of music. This could likely be automated with an interface to the music source.  You would then use the program that someone else wrote to automate you fuse selections.
With all the worry about which fuse now set aside, you could now enjoy your music without needing to think about the fuse.  Unless, you wanted to account, of course, for time of day, phases of the moon, temperature, etc.  I am sure that, for a small fee, updates would be available for every eventuality.  However, the improvement realized in SQ would be worth every penny.
Oh boy !! And so it continues ................
Did somebody forget to set out the roach motels last over the holiday? 🏨