Traditional test oracles have two problems. Firstly, several test oracles are needed for a single software program to perform different functions and maintaining a large number of test oracles is tedious. Secondly, testers usually test only the important criteria of a web application, since its time consuming to check with all the possible criteria. Ontologies have been used in a wide variety of domains and they have also been used in software testing. The main idea of this book is to define a procedure for how ontology-based test oracle automation can be achieved for testing web applications and minimize the problems of traditional test oracles. The included steps in procedure: first, the expected results are stored in ontology A by running previous working version of the web application; second, the actual results are stored in ontology B by running the web application under test at runtime; and finally, the results of both ontology A and B are compared. Evaluation includes how the proposed procedure minimizes the traditional test oracle problems and by identifying the benefits of the defined procedure. This book is for people working on ontology-based test oracle automation.