Cucumber is grown widely around the world with an annual production and productivity of 17.52 million tons and 52,504 kg/ha. The tender fruits are valued for their use as salads. It is a climbing annual, growing up to 3.0–5.50 m. The fruits contain a variety of biologically active phytochemicals, such as alkaloids, flavonoids, tannins, steroids, and saponins, among others. There are mainly processing/pickling types (harvested at the immature stage, <15 cm long, used for brining/pasteurizing) and fresh market types (harvested usually when fruits attain between 15 and 40 cm in length while still tender). The distribution of C. sativus is reported in India, China, Myanmar, and Sri Lanka. The primary genepool of C. sativus consists of its cross-compatible inter-fertile varieties under sativus, i.e., var. sativus and of the nearest relative, var. hardwickii, which is considered as the progenitor species. Globally, there are several international institutes dealing with plant genetic resources management of cucumber. Research priorities include the development of varieties with resistance/tolerance to major diseases like downy mildew, powdery mildew, anthracnose, gummy stem blight, and viral diseases; insect pests; nematodes; identification of gynoecious lines for development of hybrid varieties; development of parthenocarpic hybrids; and dual-purpose cucumbers (both for salad and culinary purpose).