Although research began in the early 1980s, the 2014 Diagnostic and statistical manual of mental disorders (DSM-V) clearly recognized that even indirect exposure to a traumatic event can have consequences on mental health. One of the possible reasons is the conceptual confusion that has arisen due to the simultaneous use of multiple terms encompassing a range of similar symptoms that indicated indirect or secondary traumatization. Secondary traumatization is most often associated with helping professions, such as psychotherapists or health care workers. However, the first studies emerged from studying families of individuals suffering from post-traumatic stress disorder. This is where the concept of secondary traumatization was created. Later, terms such as secondary traumatic stress, compassion fatigue, vicarious traumatization, or burnout developed, which are often used as synonyms, but are significantly different in essence, and the list of those who can experience consequences of indirect traumatization has expanded to include everyone who, in various ways, are caring for a traumatized individual, such as social workers, firefighters of police officers. For the assessment of secondary traumatization, instruments intended to assess the severity of symptoms arising due to direct exposure were initially used, but recent research showed that it is necessary to use specific measuring instruments that would more accurately describe the consequences of indirect traumatization. A similar thing happened with the prevention and treatment approaches - mainly interventions that have proven successful in the treatment of primary traumatization are used. However, their effectiveness is questionable because they are still understudied. The aim of this paper is to describe the concept of secondary traumatization by reviewing existing research, compare similarities and differences between related concepts, and explore available psychological measuring instruments, as well as therapeutic approaches.