It is well-known that there are many higher dimensional extended objects in string theory and M-theory, and the understanding of their properties is important. Several approaches have been applied to investigate the properties of those objects, such as super Yang-Mills theory, higher gauge theory, field theory on loop space, string field theory, double field theory, etc. In this workshop, we review and discuss the approaches taken and compare the results obtained so far. We organized several series of lectures and a number of short talks.