This book will give a solid introduction to the TTCN-3 language and its use. All the important concepts and constructs of the language are explained in a tutorial style with the emphasis on extensive examples. The book also provides the larger picture of how the testing language is related to the overall test system implementation. This book provides the perfect companion to the available TTCN-3 language standards filling the gaps like style guide, structuring, and pointing out the dangers or pitfalls based on the authorrs"s personal TTCN-3 experience from language standardization, tool implementation and applying TTCN-3 for a number of years in the real world. The style and level of the book make it suitable for both engineers learning and applying the language in the real world and students learning TTCN-3 as part of their studies. Although this book is intended to be accessible to a wide audience, it does assume that the reader has some basic knowledge of software programming.