What is Big O notation used for?

Big O notation is fundamentally used to describe the upper bound of an algorithm's time or space complexity. This notation provides a way to express the worst-case scenario in terms of how an algorithm's running time or memory consumption grows as the size of the input increases. By focusing on the upper bound, Big O helps to categorize algorithms based on their efficiency and scalability in handling larger datasets.

This concept is crucial because it allows developers and computer scientists to compare algorithms in a meaningful way, particularly for large inputs where performance differences become pronounced. Big O notation provides a high-level understanding that abstracts away constant factors and lower-order terms, focusing solely on the primary growth rate as the input size tends to infinity.

Using this notation, one can effectively communicate the performance characteristics of an algorithm irrespective of hardware specifics, giving a more universal standard for analyzing and selecting algorithms.