Validity in simple terms refers to how true, authentic or genuine something is. However, validity in research refers to the extent to which a test measures what it sets out or claims to measure.
It includes research methods as well as its design. The use of validity is very important and plays a major role in different fields of study such as science, psychology, sociology, and so on. When research is carried out in any field of study, the validity of that study will go a long way to determine whether its outcome can be useful to the general public or not.
Generally, the validity of a research study is an indication of its soundness.