This digital resource from Leica Microsystems provides detailed explanations of their microscope objective nomenclature and specifications. It is an essential guide for researchers to understand the various types of Leica objectives and their optical properties, which are critical for achieving optimal imaging results. The resource covers different classes of objectives, including achromats, semi-apochromats (FLUOTAR), and apochromats (PL APO, PL IRAPO), each designed for specific applications and levels of correction. It explains key specifications such as magnification (e.g., 5X to 100X), numerical aperture (NA), working distance, and compatible cover glass thickness. Leica objectives are known for their excellent color correction and field flatness, supporting various illumination techniques like brightfield, darkfield, phase contrast, and differential interference contrast (DIC). They are optimized for diverse applications in life science, materials research, industrial quality control, and medical imaging. Understanding these specifications allows users to select the most appropriate objective for their experimental needs, ensuring high resolution, contrast, and image quality. This resource is crucial for maximizing the performance of Leica microscope systems.