Bloodstain analysis is a forensic discipline that deals with the physics of blood and determines bloodstains left at crime scenes using visual stain recognition. It is used to shed light on the reconstruction of a crime scene which includes the cause of death starting from homicide, suicide, accident and identifies areas with a high probability of the offender leaving their DNA samples. There are documented descriptions of bloodstains at crime scenes dating back centuries, but it was the 1955 Samuel Sheppard case that spurred progress in this field. Bloodstain pattern analysis is used worldwide by scientists, police officers and doctors in an interdisciplinary manner. Both the blood itself and the surfaces on which the bloodstains are located are important in evaluating bloodstains. The umbrella organization for bloodstain pattern analysts is the International Association of Bloodstain Pattern Analysts (IABPA), which offers various forms of membership. The name of the method (bloodstain pattern analysis) is often abbreviated to BPA. To understand bloodstain pattern analysis, we must explore the origin of the process. The history of bloodstain analysis has been linked to the modern age and we also know that there have been individual case reports and descriptions of individual bloodstains. In 1895, Eduard Piotriwski, of the University of Vienna where he published and was the first to organize a study on the bloodstain pattern "On the formation, shape, direction and diffusion of bloodstains resulting from blunt trauma to the head" According to researchers and documents, Piotriwski's treatment involved covering the corner of a room with sheets of...half of paper...stained with blood, unless there was no other reason for the bloodstains. The same applies to the reverse situation if the action occurs at a point under the base of the seat. In this case the upper surface of the seat base itself will not be stained with blood. It is also possible to three-dimensionally calculate the area of ​​origin of the sketches in the given space. This depends on what phase of flight the blood drops are in. The shape of droplets depends on their angle of impact on a surface. Pictures showing different shapes in the case of different angles oversimplify this question. The difficulty lies not in the mathematical calculation itself, which is a case of trigonometric relations, but in the choice of which droplets to consider and in the differential diagnosis of whether the splashes are calculable or not. Beginners of the discipline often make mistakes in this regard.