Since the Haystack Observatory made inexpensive radio telescopes available in the last decade, attention to radio astronomy has increased. The field of radio astronomy reveals that much of what is known about the universe has been learned through the careful application of physics and the interpretation of detected signals. This textbook provides an extensive introduction to the subject of radio astronomy. The first part of the text focuses on instrumentation, with discussions on both single-dish radio telescopes and telescope arrays. The second part reviews the diverse areas of radio astrophysics and provides key findings from radio astronomical research studies.