apache & Jails

[Don Munyak]

I want to build a FreeBSD webserver to replace a M$ IIS web server.
I've started researching using Jails but am a little confused.

Given I am hosting four(4) websites, would I have four separate jails.
each jail having a separate install of apache + php + mysql ?

or would I be installing apache + php + mysql at the base system, and
then have four separate jails for each web site and database files ??

Thanks