The sequence "1, 2, 3, ..." represents the natural numbers, which are the basic counting numbers used in everyday life. These numbers start from 1 and continue infinitely, forming a simple and fundamental part of mathematics. They are used for counting objects, ordering items, and performing basic arithmetic operations. Natural numbers are often represented on a number line, where each number has a specific position. The concept of natural numbers is essential in various fields, including mathematics, science, and economics. They serve as the foundation for more complex number systems, such as integers and rational numbers.