Mathematics is the study of quantity, structure, space, and change. Mathematicians seek patterns and establish truth through rigorous logic and deduction from chosen axioms and definitions. The document then provides examples of different types of sequences including geometric sequences defined by multiplying a number each time, arithmetic sequences defined by adding a number each time, and special sequences like triangular and square numbers generated from patterns. It also discusses how to identify if a sequence is arithmetic, geometric, or harmonic based on relationships between terms.