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?
128x128rvpiano
Did somebody forget to set out the roach motels last over the holiday? 🏨
"Yet capacitors are also directional due to the wire running through them."
What is the definition of "wire" for this purpose? Surely not what first comes to one's mind.
"...we all know acoustic engineering school is a scam. They don’t teach anything to prepare you for high end audio."

Do not skip the school altogether. Apparently, more info about high-end audio education is here...

http://www.magicalwisdom.com/

Glubson, just curious, did you forget to take your smart pills this morning?