Butterfly valves are critical components in flow control systems across industries including water and wastewater, chemical processing, power generation, HVAC, and pulp & paper. This white paper offers an in-depth analysis of butterfly valve technologies, detailing end connection styles (wafer, lugged, fully flanged) and design types (resilient-seated, metal-seated, centerline, high-performance, and AWWA-compliant). It explains how to align valve selection with operating conditions such as pressure, temperature, and media characteristics, while addressing flow dynamics, sealing performance, and regulatory standards like ANSI, API, and AWWA. Practical guidance is provided for engineers and specifiers to ensure optimal valve performance, system integrity, and lifecycle cost efficiency in demanding applications.