Gellish English is a powerful Open Source language and ontology for electronic data storage and data exchange in a neutral and system independent way. Since long data storage and data communication lack a common standard universal data model as well as a common data language for database users. Various solutions have been proposed. However, those solutions either have a limited scope and are mutually incompatible or are difficult to implement. This book presents an integral solution to this problem in the form of standard Gellish English and a knowledge base, written in Gellish, whereas it is relatively easy to implement. Gellish English is the English variant of Gellish and is a structured subset of natural English. Gellish is an extension and integration of the concepts defined in various ISO and non-ISO standard data models and dictionary standards. For example, it integrates concepts from IEC 50, ISO 31, ISO 1000, ISO 1131-3, ISO 1998, ISO 10303, ISO 13584 and ISO 15926 together with material from other sources.