Social psychology - the branch of psychology that examines how individuals are influenced by others, including groups, and how individuals influence groups - is an important area of research. Social psychologists define 'group' as socially connected individuals; thus, a queue of people at a supermarket checkout, for example, falls outside this definition but people who work together in the same office fall within it.
Social psychology explores a number of areas, including obedience, persuasion, attitudes, conformity, altruism, identity, conflict and prejudice. An important concept is attribution, which refers to the explanations given for actions and events. For example, if someone does well in a job, they might explain it by saying that they are good at the job, that they were lucky or that their boss liked them. Similarly, if they don't do so well, their explanation might be that they weren't very good, that they were unlucky or that their boss didn't like them. As you might imagine, people tend to use dispositional attribution, that is, explanations involving personal qualities for events that reflect positively on them, and situational attribution, that is, explanations involving external factors such as how other people feel, for more negative events. This tendency is called self-serving bias. A related term is fundamental attribution error —the tendency to explain other people's behaviour through dispositional rather than situational attribution.