Argumentation is a process of constructing arguments and attacks between them. It drew attention of numerous scholars recently with its features and applications. This course starts with a general introduction to argumentation theory. Then, we study the main motivation and ideas behind extension-based semantics and labellings. After that, we review the quantitative and qualitative approaches for evaluation of individual arguments in an argumentation framework. We analyse and compare all those approaches using the principles from the literature. We conclude the course by providing an overview of multi-disciplinary questions, open problems, possibilities and future challenges.