a type of clinical study designed to reduce bias by ensuring that participants, and sometimes researchers, do not know which treatment is being administered. This principle helps prevent expectations or behavior from influencing study outcomes.

Single-blind trial: Only the participant does not know whether they are receiving the active treatment or a placebo/control.
Double-blind trial: Neither the participant nor the clinicians/researchers know who is receiving the active treatment or placebo/control until the study ends.

This approach strengthens the validity and reliability of the results.