Why do we use multi application server instances on the same server

Question

I guess there is a good reason, but I don\'t understand why sometimes we put for example 5 instances having the same webapplications on the same physical server.

Has it

Answer 1

An additional reason to use mutliple instance is serviceability.

For example if you multiple different applications for multiple customers then having seperate instances of the appserver for each application can make life a little easier when you have to do an appserver restart during a release.