The aim of the present volume is to offer a comprehensive and up-to-date survey of phonetic and phonological research on Iranian languages and dialects. Iranian languages—spoken by tens of millions across a wide geographical area extending from the Middle East to Central and South Asia, and diaspora communities—exhibit considerable variation in phonetic detail and phonological structure. Bringing together leading scholars from around the world, this handbook provides original empirical findings, theoretical insights, and experimental results that explore various aspects of sound systems of Iranian languages and dialects. This introductory chapter provides an overview of the handbook, outlining its purpose, structure, and the key themes and contributions of each chapter.