The important and main aim of this book is to understand the concept of Ontology used in Business Activities. In this book we also understood basic knowledge about the Ontology Web language which we are using during the implementation of the Business Activity of two Running Businesses. We also learned about the concepts of semantic web ,business modelling and the four important phases of semantic web modelling. All these concepts are used for developing my own Business Activity Ontology. When we go through the book we can easily understand how ontology works and also understand some important terms which we used during implementation and designing of our Business Activity Ontology.