Final answer:
Bloodletting techniques included the use of leeches, cupping, and scarification, which were intended to remove excess blood, believed to cause illness. These practices have been largely abandoned due to the advancement of medical knowledge and evidence of their ineffectiveness and harm.
Step-by-step explanation:
These methods were believed to restore balance in the body by removing excess blood, which was thought to be the cause of illness. Leeches were applied to the patient's skin to suck out blood, cupping used heated cups to create a vacuum on the skin that would draw out blood, and scarification involved making small cuts on the skin to release blood. Over time, as medical knowledge advanced, the practice of bloodletting was largely abandoned due to doubts about its effectiveness and evidence of its potential harm to patients.