The sequence "100001000" is a binary number, which is a system that uses only two digits: 0 and 1. In this case, it represents the decimal number 512. Binary numbers are commonly used in computer science and digital electronics because they align with the on/off states of electronic circuits. In the context of computing, binary is fundamental for data representation and processing. Each digit in a binary number is referred to as a bit, and groups of bits can represent various types of information, such as numbers, letters, and images, in digital systems.