The active response is in the one where our body created its own antibodies for a pathogen to which it has been exposed to and the exposure can be natural or artificial. The natural is by getting the disease and building an immune response when the lymphocytes generate specific antibodies to the pathogen. The second way is by arficially being exposed to the pathogen without getting sick but still de able to differentiate and create specific antibodies. This is done with vaccines. They are solutions with the antigen or the dead pathogen or an attenuated one that triggers the immunological response as a normal infection would.