Than is used to compare two things, showing a difference between them, as in 'bigger than' or 'smarter than'. It often comes after comparative words like 'more', 'less', 'better', or 'worse'.
From Old English *þonne* or *þan* used in comparative constructions, related to 'then'. Over time, English separated their jobs: 'than' for comparison and 'then' for time.
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