The two principal purposes of an internship as I see them are to learn and to network. (social.hays.com)
I've written extensively on this blog about money - sucking awards programs whose principal purpose is to create income for the sponsors, rather than recognition for the entrants. (victoriastrauss.com)
Holding company A corporation whose principal purpose is to hold investment assets, such as shares in other companies and portfolio investments. (taxplanningguide.ca)