Sequence is ordered list of numbers following pattern. Sequence a₁, a₂, a₃, ... where aₙ is nth term. General term aₙ defines entire sequence. Example: aₙ = 2n-1 gives 1, 3, 5, 7, ... (odd numbers). Types: Finite (specific number of terms) vs Infinite (continues indefinitely). Representation: (1) List form; (2) General term; (3) Recursive (each term based on previous). Identifying pattern: Look for differences, ratios, or algebraic relationships. Exam tip: Express general term clearly. Verify by substituting n = 1, 2, 3. Understand context (arithmetic, geometric, other).