Psychodynamic psychotherapy is a type of psychotherapy, usually meeting about once or twice a week. It is different from other systems of psychotherapy, for instance psychoanalysis or cognitive therapy in that it uses a range of different techniques, applied to the client considering his or her needs. A psychodynamic therapist may find that Object relations theory may be best for a client with Borderline Personality Disorder, and the next client who displays some anxiety in her marriage may be given some cognitive therapy to give symptom relief.
Most psychodynamic approaches are centered around the idea of a maladapted function developed early in life (usually childhood) which are at least in part unconscious. This maladapted function (a.k.a. defense mechanism) does not do well as it formed instead of a normal/healthy one. Later on the client will feel discomfort when they notice (or do not notice) that this function causes problems day to day. The psychodynamic therapist will first treat the discomfort associated with the poorly formed function, reveal to the client that such a function exists, then change, remove or replace it with a proper one.
Psychodynamic psychotherapy involves a great idea of introspection and reflection from the client. Usually this level of insight is unfettered when the client wants to be helped or is pushed by family or friends. Speaking to this is also the client's ability to dive into their past; they must possess enough resilience and ego-strength to deal with/use the onslaught of feeling a new perspective brings. The more fragile client may be treated with a different treatment, for instance, cognitive therapy.