A zigzag sequence is a sequence of numbers where the elements alternate between being greater than and less than their neighbors. Specifically, for a sequence to be classified as zigzag, it must follow the pattern of either increasing and then decreasing or decreasing and then increasing. This pattern can be observed in various mathematical contexts and is useful in analyzing trends. Zigzag sequences can be applied in different fields, including mathematics, computer science, and data analysis. They help in identifying fluctuations in data sets, making them valuable for tasks such as signal processing and financial analysis. Understanding zigzag sequences can enhance pattern recognition skills.