Complexity Analysis is a method used in computer science to evaluate the efficiency of algorithms. It focuses on measuring the time and space resources an algorithm requires as the size of the input data increases. By understanding these resource requirements, developers can choose the most suitable algorithm for a given problem. There are two main types of complexity: Time Complexity and Space Complexity. Time Complexity assesses how the execution time of an algorithm grows with input size, while Space Complexity evaluates the amount of memory an algorithm uses. Together, they help in comparing and optimizing algorithms for better performance.