You need

• a webserver like Apache;
• PHP >= 5 installed to be interpreted by the webserver (apache2-mod_php5) and to be run on command line, with the following modules: GD module (php5-gd), MySQL module (php5-mysql), Multibyte string module (php5-mbstring);
• MySQL >=5 (I recommend the community-server version from Oracle);
• the cron daemon (available all unix/linux systems, you need a replacement on Windows systems); and
• the webalizer log file analyzer (only needed if you want to analyze your server logs).

All of these software packages are part of standard Linux distributions like RedHat, SuSE and others. However, ORSEE runs on Microsoft Windows Servers as well, since Apache, PHP and webalizer run there, too. Only for cron you will have to find a substitute (e.g. pycron).