Every dairy operation should produce máximum quantities of high quality milk. Since mastitis is the main threat to milk quality and therefore, dairy farm profits, it is essential to identify the etiological agents to implementing intramammary infection treatment and/or establishing control programs. This handbook, which highlights the importance of achieving high quality milk levels through a practial and visual approach, has been written by authors with a wide experience in this field. Numerous graphic resources have been included to complement the information provided and make the contents more understandable and accessible to readers.