A sequence is a group of things that fit together in a certain way. In math, a sequence is a set of numbers that are in the same order and follow the same pattern. Sequences can be either finite or infinite. Finite sequences have a set number of terms, while infinite sequences have an unlimited number of terms. In Chapter 13 of Class 11 RS Aggarwal, students learn about the Arithmetic Sequence, the Geometric Sequence, and the Fibonacci Sequence, which are all examples of finite and infinite sequences.