An extrovert is someone who is outgoing and sociable and who readily engages with the outside world. One who does not need much engagement with other people or the outside world is called an introvert.
Extroversion is a widely studied personality trait that is measured by several popular personality tests used to assess candidates for employment and as part of a comprehensive assessment for personality disorder. The most scientifically valid test of this type is called the NEO-PI. The most popular test that assesses extroversion, the Myers-Briggs Type Indicator, has poor test-retest reliability, so it is not a good selection tool to use when evaluating candidates for employment.