Electronic service, or e-service, is a key concept in today’s e-Government development. The availability and quality of electronic services are important indicators of e-Government maturity. However, we argue that our understanding of the concept e-service is poor and we show that the ambiguity surrounding the concept creates problems when building ontologies and thus makes it difficult to achieve better interoperability between systems. We thus propose a model for e-services building on a framework for categorizing services using some basic terms. In this way we can describe and model various types of communication between citizens and public agencies based on a consistent set of elementary categories. Our model also draws on EU’s proposed Core Public Service Vocabulary (CPSV). The paper is conceptual and is mainly based on a literature review.