A numerical sequence is a list of numbers arranged in a specific order, following a particular pattern or rule. Each number in the sequence is called a term, and the position of each term is usually indicated by its index. For example, in the sequence 2, 4, 6, 8, each term increases by 2, making it an arithmetic sequence. Numerical sequences can be finite, having a limited number of terms, or infinite, continuing indefinitely. They can also be classified into various types, such as arithmetic, geometric, and Fibonacci sequences, each defined by its own unique pattern of progression.