排序 means 'to sort' or 'to rank'—arranging items in a specific order, such as ascending, descending, alphabetical, chronological, or by priority. The character 排 (pái) means 'to line up' or 'to arrange', while 序 (xù) means 'order' or 'sequence'; together, they literally convey 'arranging into order'. This term is widely used in both everyday and technical contexts: organizing lists, ranking search results, sorting data in spreadsheets, or arranging students by height or test scores.

It functions primarily as a verb and commonly appears in compound verbs like 排序算法 (sorting algorithm), 按...排序 (to sort by...), or with aspect markers like 正在排序 (sorting now) or 已经排序 (already sorted). Though it can occasionally function as a noun (e.g., 数据排序), its verbal use dominates. Unlike the more colloquial 排队 (to queue), 排序 implies logical or systematic arrangement rather than physical waiting.