The purpose of this article is to introduce the reader to the important design characteristics of sampling and sample preparation systems for process analytical measurements, as well as to discuss several of the most commonly used configurations for gas‐ and liquid‐phase process streams. Design criteria essential to the success of any process analyzer installation are discussed at length, and the pitfalls associated with neglecting these items are highlighted. This article provides an overview of what must be considered when building the interface between the analytical instrument and the process stream. It is not intended to be a comprehensive dissertation on the subject or a tutorial. The reader is referred to literature references and textbooks for detailed explanations and relevant design formulae. In addition, we also provide several sections regarding calibration procedures, maintenance concerns, and safety considerations.