**1. Introduction**

Nailfold capillaroscopy (NFC) is a noninvasive bedside tool for the assessment of capillary microcirculation and its changes. The history of this technique dates back to over four centuries, with J C Kohlhaas's first description of capillary loops in nailfold using basic optical magnification. However, the utility of NFC in rheumatological diseases came to the forefront after the studies of Maricq and Le Roy in 1973 [1]. They systematically described the capillaroscopic patterns in patients of rheumatoid arthritis, systemic lupus erythematosus (SLE), and scleroderma (SSc) using a wide-field stereomicroscope of 12× magnification. From then on, NFC has evolved to be an indispensable tool for the rheumatologists in the evaluation of patients with connective tissue diseases. NFC is now included in the recent American College of Rheumatology/European League Against Rheumatism classification criteria for SSc [2]. In the current chapter, we shall highlight the physiology, preparation, instruments, and NFC parameters in various rheumatic diseases including SSc.
