Maize (Zea mays L.), commonly known as corn, is a crucial crop grown worldwide for human consumption, animal feed, and biofuel production. It is primarily cross-pollinated and has a wide genetic potential, with genetic resources from wild species preserved in gene banks. Maize is considered the “queen” of cereals due to its high genetic yield potential and ability to thrive in various agroecological conditions. C4 maize crops play a vital role in ensuring food security and sustainability in the face of climate change. Maintaining diverse genetic backgrounds through the study of genetic diversity is essential for developing climate-resilient maize varieties. Crossbreeding popular cultivars with indigenous ones enhances genetic diversity and introduces beneficial traits, leading to the emergence of new alleles. Genetic improvement can significantly reduce the impacts of biotic and abiotic stresses while increasing yield potential. The development of disease-resistant, stress-tolerant, and nutritionally enhanced cultivars involves both traditional and molecular techniques. This chapter provides a comprehensive overview of the origin and botanical classification of maize, its types, significance and uses, domestication, selection and early advancements, current cultivation practices, breeding goals, germplasm biodiversity and preservation, cultivar characterization and phylogeny, conservation of genetic resources, cytogenetics, traditional breeding methods, improvement strategies, the role of biotechnology, molecular breeding, applications of tissue culture, genetic engineering and gene editing, mutation breeding, conventional mutagenesis, and maize hybridization.