A programmer writes computer instructions in logical order to solve problems or perform tasks. Key competencies for a programmer include analytical thinking, being client-focused, good communication skills, continuous learning, being results-oriented, and being a team player. Programmers also need technical skills like programming, software development, business analysis, database design, information security, and identifying emerging technologies and platforms. Programmers can specialize in areas like systems programming, application development, game programming, or web development.