An amortized analysis is a method for analyzing a given algorithm's complexity, or how much of a resource, especially time or memory, it takes to execute. It guarantees the average performance of each operation in the worst case.
The asymptotic analysis gives worst case analysis of each operation without taking the effect of one operation on the other, whereas amortized analysis focuses on a sequence of operations, an interplay between operations, and thus yielding an analysis which is precise and depicts a micro-level analysis.
Three most common techniques used are aggregate analysis, accounting method and potential method.
The aggregate method, in which the total running time for a sequence of operations is analyzed.
The accounting (or banker's) method, in which an extra charge would be imposed on inexpensive operations and use it to pay for expensive operations later on.
The potential (or physicist's) method, in which a potential function would be derived characterizing the amount of extra work that can be done in each step. This potential either increases or decreases with each successive operation, but cannot be negative.