Steam cleaning is generally the best method for cleaning carpets because it removes over 90% of dirt and kills 99% of bacteria and viruses. 
Along with the right chemicals for your carpet, The HWE (Hot Water Extraction) approach penetrates stains and dirt with water/steam over 100 degrees Celsius to break down all the unwanted build up whilst the powerful USA made truckmounted machine extracts the water containing all the nasty ingredients to leave your carpet looking and smelling much better.