Public health is concerned with protecting the health of entire populations. Epidemiology is the study and analysis of the cause, effect and pattern of diseases. It is the key discipline of public health and identifies risk factors for disease and targets for preventive healthcare. The main part of Epidemiology is to gain new understanding of the correlation of genetic and environmental factors affecting on human health, providing the scientific basis for translation of this knowledge to global health. It is applied to cover the description of epidemic diseases and health related conditions like obesity and high blood pressure.

Nutrition is the supply of materials (food) required by organisms and cells to stay alive. As per the science, nutrition is the science or practice of consuming and utilizing foods. It is the application of nutrition principles to improve or maintain optimal community health and targets the community through enhancements in health policies, health systems, health technology and environmental health. A nutrient is a source of nourishment, a component of food, for instance, protein, carbohydrate, fat, vitamin, mineral, fiber, and water. Community nutrition incorporates individuals and interpersonal-level mediations that make changes in learning, states of mind, conduct and wellbeing results among people, families or Small, focused on gatherings inside a community.

Nutritional science is the study of how an organism is nourished and includes the study of Nutrition and metabolism. Nutritional science includes a wide spectrum of disciplines. Nutrients must be obtained from diet, since the human body does not synthesize them and are used to generate energy, notice and respond to environmental surroundings, move, excrete wastes, respire. Healthy food habit is becoming ever more of a science, with new research showing us which foods may decrease our risk of disease, and which are progressively pointed to as the culprits behind ill health. Researchers are looking to better recognise how nutrients work in our bodies by investigating the diets of people with heart disease, cancer, and other diseases, along with research aimed at helping people to lose weight, or maintain weight loss. There are various classes of nutrients such as carbohydrates, lipids, proteins, water, vitamins, and minerals which are required for the body to function and maintain overall health.

Nutrition Health Policy rather than considering the health of an individual, we will consider the health of the entire community or certain population. It mainly focuses on preventing infectious diseases, removing contaminants from food and drinking water, reducing pollution, by public health policies (for example administering vaccines for various diseases) etc. since they can affect the entire community. The health of the nation can be influenced by public health policies, such as a tobacco control policy, and by policies in many other sectors. For example, transportation policies can encourage increased physical activity and school nutrition policies can ensure healthier meals are provided in schools. Many national health strategies, plans, and initiatives, such as Healthy People 2020, have policy implications. Policy decisions are also frequently reflected in resource allocations.

Mental Health is a state of well-being during which each individual realises his or her own potential, can cope up with the conventional stresses in life, can work productively and fruitfully, and is ready to give a contribution to his or her community. Many researches show that high levels of mental health are related to increase in learning, creative thinking and productivity, more pro-social behaviour and positive relationships, and with improved physical health and life expectancy. In distinction, mental health conditions causes’ distress, impact on day-to-day functioning and relationships, and are related to poor physical health and premature death from suicide.

Public Health Nursing or community health nursing is a Nursing speciality aimed to improve public health. It is the combination of Nursing and Public health practice used to protect and promote the health of population. It combines all the principles of professional, clinical nursing with public health and community practice. Public health nurses work within communities and focus on different areas to improve the overall health of the people within that community by educating individuals about the healthy lifestyles like educating benefits of various fruits and vegetables, educating about healthy eating plate, educating healthy eating pyramid.

Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary heart disease, angina, heart attack, congenital heart disease and stroke. It's also known as heart and circulatory disease. Its most common types are: Coronary artery disease, High blood pressure, Cardiac arrest, Congestive heart failure, Arrhythmia, Peripheral artery disease, Stroke, Congenital heart disease

Occupational health and safety (OHS) relates to health, safety, and welfare problems within the work. OHS includes the laws, standards, and programs that area unit geared toward creating the work better for employees, together with co-workers, family members, customers, and alternative stakeholders. Improving a company's occupational health and safety standards ensures smart business, a stronger brand image, and better worker morale.

An emerging infectious disease (EID) is an infectious disease whose incidence has accumulated within the past twenty years and could increase in the near future. Emerging infections account for a minimum of 12-tone music of all human pathogens. EIDs are caused by recently known species or strains (e.g. Severe acute respiratory syndrome, HIV/AIDS)[2] that will have evolved from a illustrious infection (e.g. influenza) or spread to a new population (e.g. West Nile fever) or to a region undergoing ecologic transformation (e.g. Lyme disease), or be reemerging infections, like drug resistant tuberculosis. Nosocomial (hospital-acquired) infections, like methicillin-resistant staphylococcus aureus are rising in hospitals, and intensely problematic in this they're resistant to several antibiotics.

Public health challenges are not just local, national or regional. They are global. These are not only within the domain of public health specialists. They are among the key challenges to our societies. They are political and cross-sectoral. They are intimately linked to environment and development. They are an important part of national, regional and global security. In today's world we need a change in awareness towards the idea of building global public goods that can help us reap the huge potential benefits of globalization while at the same time keep in mind about the risks and vulnerabilities that comes with it. The main question is one of taking responsibility, of using our democracies to promote change. Investing in health is an obvious choice. It saves lives, millions of lives. But it will also rise up the economy, of poor countries and of the world.

Oral health is integral to general health and is essential to the overall health and wellbeing of all individuals. The early identification of oral disease may contribute to the early diagnosis and treatment for a number of systemic diseases.Oral health means more than healthy teeth. The word “oral” refers to the mouth which includes not only the teeth, gums and supporting tissue, but also the hard and soft palate, the mucosal lining of the mouth and throat, the tongue, the lips, the salivary glands, the chewing muscles and the jaw. The salivary glands are a model of other exocrine glands, and an analysis of saliva can provide clues of overall health or disease. A thorough oral examination can detect signs of nutritional deficiencies as well as a number of systemic diseases, including infections, immune disorders, injuries and some cancers.

Sexual and reproductive health (SRH) is an essential component of the universal right to the highest attainable standard of physical and mental health, enshrined in the Universal Declaration of Human Rights and in different international human rights conventions, declarations, and consensus agreements. Sexual and reproductive health desires must be met for both men and women. Human rights standards need states to respect, protect, and fulfill the right to sexual and reproductive health, and states should conjointly ensure that people have the chance to actively participate in the development of health care policy and in individual care decisions —including determining whether and when to have children and in protecting the rights of others to sexual and reproductive health, together with through ensuring violence-free relationships and homes and in seeking info, education, and look after one’s youngsters.

Health Informatics is the practice of collecting, analyzing and managing health data and using medical concepts in conjunction with health information technology systems to help clinicians provide better healthcare. Health informatics, also known as healthcare informatics, has grown as an evolving science with the expansion of electronic health records (EHRs) and health data analytics systems. Public health informatics is the application of computer science, information and technology to the administration of public health, including disease surveillance, prevention, preparedness and health education, according to the American Medical Informatics Association.

Climate change, along with different natural and human-made health stressors, influences human health and illness in various ways. Some existing health threats will intensify and new health threats will emerge. Not everyone is equally at risk. Important considerations include age, economic resources, and location. Public health is often laid low with disruptions of physical, biological, and ecological systems, including disturbances originating here and elsewhere. The health effects of those disruptions embody increased respiratory and cardiovascular disease, injuries and premature deaths associated with extreme weather events, changes within the prevalence and geographical distribution of food- and water-borne diseases and different infectious diseases, and threats to psychological state.