Why do we do the things we do? Why do some people like hot drink while others prefer cold one? How can some of us put a name to every single person we have ever met while others struggle even to remember our own telephone number? Why do some people always seem happy and successful while others see no choice but to end their painful lives in suicide? Why some people seem optimistic while another seem pessimistic? Why some persons have negative attitude toward an object or event while others have positive one to the same object or event? Why some individuals have divergent thinking while another have invergent one? Is there difference in learning, achievement and intelligence between male and female? (Murry, 2015, Robins, Tracy, & Sherman, 2007). Why some people have residence personality while another have dignity trait in personality? Can do we predict individual's behavior? Can we change the person's attitudes and interests? Are some persons more predisposing to anxiety disorders than another's? These are the sorts of questions we can try to answer through psychology: "the science of human behavior and mental health". In this article review, we will briefly explore the different branches of psychology and get a quick overview of the kinds of things psychologists do from practical and methodological perspective (Abdullah, 2015).

Many people I know don't really question why they or other people behave the way that they do, why they feel how they feel (meta-emotions), why they relate to others the ways that they do (social perception and cognitions), or why the same patterns play out again and again in people's lives. To think psychologically, to me is to draw links with what has been learnt from early experiences or relationships in the past, what the antecedents and consequences are to behavior, what triggers particular feelings or behaviors. We can constantly sought to put more psychology in our lives and more life in our psychology (Lemma, 2005, Zimbardo, 2004).

 Psychology is the science of behavior and mind embracing all aspects of conscious and unconscious  experience as well as thought. It is an academic discipline  and a social science, which seeks to understand individuals and groups by establishing general principles and researching specific cases. Psychology is the study of people's behavior, and mental operations. It also refers to the application of the knowledge, which can be used to understand, predict and control events or behavioral phenomena (e.g. treat mental health issues, and improve education, employment, and relationships). The subject lies at the intersection of applied, educational, and theoretical science. The applied and sub area of psychology are Education, Business/Carrier and industry, Media, Medicine, Sports, Military. Because we are frequently exposed to the work of psychologists in our everyday lives, we all have an idea about what psychology is and what psychologists do. Most psychologists work in research laboratories, hospitals, and other field settings where they study the behavior of humans and animals (Murry, 2015, Abdullah, 2015).

In its primary form, psychology studies people- who and what they are. It looks into why they act and think the way they do and how someone can improve himself or herself. Therefore, everything a person does is connected to the subject. Psychology allows people to understand more about how the body and mind work together. This knowledge can help with decision-making, adjusting and coping with situations. It can help with time management, setting and achieving goals, and living effectively. The science not only allows people to be more successful, but it can also influence their health. It helps many tackle their mental illnesses so that they can continue living their lives. Psychological studies have also aided in drug development and the ability to diagnose various psychoneurological diseases (such as Alzheimer and Parkinson's) and rehabilitate with handicap and disabilities.

People frequently make important decisions based on their assessments of the personality of others. A decision regarding who should baby-sit your children will depend at least partly on how reliable and conscientious you judge your choices of baby-sitters to be; and whom you decide to marry might depend on how trustworthy and loving you judge your dating partner to be. People will make better decisions when they accurately judge the personality of others, and knowledge about the process of accurate judgment may help people make more judgments that are accurate. One important aspect of the process of accurate judgment concerns the person making the judgment, or the judge. Theorizing about the good judge posits that a good judge should be knowledgeable about how personality relates to behavior, have high levels of cognitive ability and general intelligence, and be motivated to be accurate, among other characteristics It is also possible that good judges are people who are able to obtain a relatively large amount of useful information about their targets.

I can personally testify to the importance of the subject. Psychology has helped me to understand myself and others (self-concept). I will enjoy and write on the topics that I like as researcher and professional (interests attitudes and motivations)). I can understand who I am and look at events on a more positive aspect (optimistic) and to go on through decision-making (problem –solving). Whenever I have a problem, I can handle it better via coping skills and adaptive behaviors. Behavior is what makes us gentle and sober and behavior is what makes us human. It’s one quality that we have developed that throws us in the good light no matter what position we hold in the society or how rich we are (Abdullah, 2012).

We do need psychological science because we cannot depend on our common sense to figure thing out. Common sense describes what has happened more easily than it predicts what will happen. In addition, common sense may consent. Explain why using our intuition about everyday behavior is insufficient for a complete understanding of the causes of behavior. Additionally, describe the difference between values and facts and explain how the scientific method is used to differentiate between the two (Robins, Tracy, & Sherman, 2007).

Psychology as a science of behavior
Behavioral psychologists defined behavior as "Any observable and measurable action". That is meaning overt/explicit and observable response, which represent the objective of the psychological science. On the other hand, the behavior and reaction can be unobservable or implied/latent such as “mental state and some neuropsychological reaction”. Therefore, it is very important to recommend that the definition should be global as the following:

Psychology is "the science of behavior. And the behavior is any responses or actions which can be observable or unobservable (overt/explicit and covert/ implied)". Or "psychology is science of behavior and mental state". According the behavioral approach in psychology there are some principles for explaining behaviors:

• Behavior is largely a product of its environment.
• Behavior is strengthened or weakened by its consequences.
• Behavior responds better to positive rather than negative consequences.
• If a behavior increases, (happens more often) someone or something is reinforcing it.
• Whether a behavior is punished or reinforced is only known by the behavior in the future (reinforcement = strengthens and punishment = weakens).
• Past behavior is the biggest predictor of future behavior.
• Positive/Negative reinforcement does not mean good or bad. It means to present (add) or remove (take away).
• Problem behaviors compete with appropriate behaviors and usually win (they are easier and more rewarding).
• A person might not have learned the appropriate forms of achieving the same function.
• Successful changes will depend on physical effort involved, schedule of reinforcement, and how many times they are required to perform (Skinner, 1987, Abdullah, 2015, Glassman & Hadad, 2009, Murry, 2015).

Science is aimed to understand, explain, predict and control the subject (object/phenomena or event). Psychology is the science of behavioral and mental state/events. In addition, the behavior may be overt or covert. Investigating the covert (inside) behaviors can be depending on the manner and expressible behaviors. Psychologists have dozen of instruments and tools for investigating the behavioral phenomena, e. g. tests, scales, self-reports, interviews, case-study, projective techniques, observations, neuropsychological assessment procedures. The aims of this science are to: understand/explain, predict and control the behavior (American Educational Research Association 2006).

Understanding behavior intended to explain the factor and cases of behavior; in addition, predicting behavior is depending on the most important characteristic of behavior that is characterized "stability or consistency", while controlling behavior is depending on the most important characteristic of the behavior, which is characterized "changeable". Characteristics of behavior stability and changeable, direct our attention to the relatively stability of the behavior and mental state, and if the stability is absolute we cannot modify behavior. On the other hand, it is very important to differentiate between trait and state. The state is most stable than trait, and trait is most stable than aspect or characteristic. State more everlasting than trait and characteristic, on one hand, and trait includes many characteristics on the other hand. Additionally, personality is the organized collection of all the three elements. According to this scientific perspective, personality has been defined as “the relatively stable and enduring aspects of individuals which distinguish them from other people and form the basis of our predictions concerning their future behavior.” (Robins, Tracy, & Sherman, 2007).

The last point is the most important. Since we seek predictability, we seek to learn those things about our fellow beings that will enable us to predict what they will do – in given situations. The better we know them, the more likely we are to be able to make such a prediction. Personality, in this sense, is not about social skills. It is not about evaluation. It is about seeking those aspects of a person, which can be said to account for their behavior and predict it in the future (Furr, 2009, Abdullah, 2016). Some researchers hold that personality becomes fixed by age 5. This is most unlikely and current research indicates that our attitudes, belief systems and aspirations – components of personality – while difficult to change, continue to adapt during life. However, if the word “personality” means anything, it must refer to those more stable motivations to our actions.

When considering personality stability, researchers can think of it at the individual level (e.g., how is 18-year-old you different than 38-year-old you?) or at the group level (e.g., how are most 18-year-olds different from most 38-year-olds

In sum: The study of human behavior and human dynamics are essential for anyone to cultivate positive relations with others and avoid unnecessary conflict. The study of human behavior and dynamics needs to be part of any educational curriculum program. The study of human behavior helps one to understand that it is part of our human nature to make mistakes, that good intentions lead to mishaps and that stuff happens. We have to be cognizant of this knowledge in order to get on with life. In addition, if we are to value positive social relations and getting along with others, then we need to consider the consequences of our actions and behaviors in relation to judging others.

We should all study human behavior to maintain positive social relations with others and in order to contribute to a harmonious society. Social skills should not be left to chance. Institutions should not only prepare students for the workplace but to live and succeed in a dynamically changing society. Social skills need to be taught. The reasons to study Psychology are: (1) Understanding Basic Psychological and Scientific Principles, (2) Critical thinking, (3)More Effective in the workplace, (4) Understanding of Relationships and Well-Being, (5)Improves Employability, (6) self –awareness and self-acceptance, (7) prevention mental disorders and promotion mental health and well-being, (8) cope with stress and learn adaptive and healthy behavior to events and situations, (9) normal development and be effective personality. Consistency and changeable are the most important principles for healthy and developed personality.