Top Task Analysis is used to identify the most important tasks of anapplication for users by letting the users select them in an onlinesurvey. The result is an evidence-based statement on the top tasks,thus the most important tasks of a product for the users. Thisallows internal resources to be concentrated on the most importantareas of a user interface. The parts of the application that aremost important for the user are optimized first. The content isstructured in a way that the most relevant content from the user'sperspective can be found most quickly. The Top Task Analysis is alsouseful to determine which contents and areas of the product are mostimportant before developing a new product.
Find a detailed description of the method here: Top Task Analysis