In the last decades, terrorist actions have shaped a challenging scenario of threat around the world. Today we are faced with several countries and sectors of society where expensive financial resources are used to prevent terrorist acts. In the civil aviation sector, this scenario of international concern with the prevention of terrorist or unlawful acts is formally established through the International Civil Aviation Organization (ICAO). Some experts even claim that human resources are the weakest link in this "chain", but given the due attention, it can become the strongest link or even the most fundamental element of the security system as a whole. It is for no other reason that the study of errors and human factors in airport security and screening operations has been so vast in international literature. The book is about this issue, errors and human factors in airport security operations, which deals with the investigations contained in previously written articles. The authors have investigated the presence of human errors and factors, and their potential effects, in the security operations in the passenger screening checkpoints of the main Brazilian airports.