Failure analysis plays a major role in all areas of the semiconductor company especially during product development cycle, 1st silicon stage, or in wafer processes and fabrication as well as assembly and package development. Different companies have different FA flows but all FA steps will need to start with fault isolation. Fault isolation is the step to narrow down the focus area of a failing component or product to a manageable area that will allow us to (a) improve success of finding the defect that is causing the failure and, (b) significant speed up turn-around time for analysis.This paper provides an overview of all the available failure analysis on fault isolation methodologies and tools, for device/product level and expanding to package/assembly and PFA level isolation. The aim of the paper is to provide sufficient depth to each topic including some case studies to emphasize the key points related to each methodology. The tutorial will also cover some future directions/roadmaps.