Space is the boundless three-dimensional extent in which objects and events have relative position and direction.

Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells.

The right to health is the economic, social and cultural right to a universal minimum standard of health to which all individuals are entitled.

In epidemiology, a risk factor is a variable associated with an increased risk of disease or infection.

Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent (known as the immunogen).

Health insurance is insurance against the risk of incurring medical expenses among individuals.

Men's health refers to health issues specific to human male anatomy.

Mental health (or behavioral health) is a level of psychological well-being, or an absence of a mental disorder; it is the "psychological state of someone who is functioning at a satisfactory level of emotional and behavioral adjustment".

Pediatrics (also spelled paediatrics or pædiatrics) is the branch of medicine that deals with the medical care of infants, children, and adolescents, and the age limit usually ranges from birth up to 18 (in some places until completion of secondary education, and until age 21 in the United States).

Within the framework of the World Health Organization's (WHO) definition of health as a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity, reproductive health, or sexual health/hygiene, addresses the reproductive processes, functions and system at all stages of life.

Reproductive health implies that people are able to have a responsible, satisfying and safer sex life and that they have the capability to reproduce and the freedom to decide if, when and how often to do so.