If you're a sysadmin or if you run a Perl software development environment, you might want to give your users or developers the possibility to install Perl modules from CPAN into their private user-space. This could be helpful for trying out new modules or playing around with modules that might be used in production at a later time. Or, if a developer wants to test a new version of a module without overwriting the system-wide installed version of that module.

Here is a step by step instruction how you could set-up user-space CPAN support.