The Semantic Web brings a new way of representing information, thereby making it more understandable for computers. Ontologies are the building blocks of the semantic web framework and have thus become its cornerstone, as they allow sharing and reusing - in a standardized way - heterogeneous data between applications of different nature. In this sense, ontology capabilities have paved the way for new, innovative trends in web-based applications across multiple domains, including medicine, e-learning, and ontology and software engineering. This Special Issue explores how semantic web application trends are being developed as of the popularity of semantic web technologies. To prepare this compilation of works, the editors promoted an open call for papers through multiple international email lists and received a vast number of prospects. Then, every paper was thoroughly peer-reviewed by subject matter experts. The peer-review process resulted in the selection of eight high-quality manuscripts compiled and published in this Special Issue.