IonCube Loader is a software tool, that is required to run files that are encoded with ionCube PHP Encoder. The latter is an app employed to make PHP code human unreadable, so as to protect it from reverse engineering and illegal usage. Many script-driven applications, especially discussion forums, content management systems and e-commerce solutions are encrypted with ionCube PHP Encoder, so when you obtain a script and you notice that ionCube is among the hosting environment prerequisites, you have to ensure that your website hosting server has the instrument pre-installed. Although it's not that difficult to set it up when you have your own server, it's almost impossible to do that on a shared web hosting server due to the fact that the PHP environment will have to be precompiled and all of the clients on the server shall be affected.