Group discussion is used to evaluate candidates for admissions and jobs by having them participate in a group discussion. It allows evaluators to assess candidates' linguistic abilities, ideas, and how they work in a group. Group discussions involve 6-12 participants discussing a topic for 15-30 minutes while being monitored by panelists and moderators. Candidates are evaluated on various communication and soft skills like subject knowledge, originality, presentation, analytical ability, and leadership. The document provides guidance on how to effectively participate in a group discussion by remembering to think before speaking, backing up points, and avoiding common mistakes.