CodeIgniter is an application development framework. People who develop websites using PHP, it is a toolkit for them. This toolkit provides libraries for general or frequently required tasks as well as a simple interface and logical structure to access these libraries. Thus you have not to write all codes from the scratch and it saves a lot of time so that projects run faster.
CodeIngniter is a framework with small foot print and clear documentation. It has Broad compatibility with standard hosting accounts that run a variety of PHP versions and configurations. It doesn’t need a template language as well as has featured database classes with support for several platforms.
Benefits of CodeIgniter
Support for hooks and class extensions and query builder database
Supports attachments, html/text email, multiple protocols Image
Benchmarking, full page caching, error logging, application profiling
Class as FTP, calendaring, user agent, zip encoding, template engine, unit testing
Form and data validation
Security and XSS filtering