Credits
CodeIgniter was originally developed by Rick Ellis (CEO of Ellislab, Inc.). The framework was written for performance in the real world, with many of the class libraries, helpers, and sub-systems borrowed from the code-base of ExpressionEngine.
It is currently developed and maintained by the ExpressionEngine Development Team.
A hat tip goes to Ruby on Rails for inspiring us to create a PHP framework, and for bringing frameworks into the general consciousness of the web community.