Fip?

Ok i see some people on here talking about how there cats have FIP.
I was wondering, what exactly is it? I have never heard of it before this site.
How do cats get it?
What are the signs that they have it?

thanks, im just curious

It's Feline Infectious Peritionitis- it is fatal. There are two types wet and dry. It is also commonly misdiagnosed because it mimics other diseases. There are no diagnositic tests available to accurately tell if you cat has this. Symptoms
Fevers of unknown origin
Diarrhea
Weight loss
Poor appetite
Lethargy
Balance and neurological problems
Litter box accidents
Wet pouch forms underneath the skin (wet effusive form only)

They have determined that FIP is not contagious as originally thought