Epithelial tissues constitute the outer surface of the body, line most internal organ cavities, and form a significant portion of glandular structures. Malignant neoplasms originating from epithelia typically begin as hyperplasias progressing to carcinomas in situ, which serve as non-obligate precursors to invasive lesions and advanced metastatic disease. This chapter compares the fundamental characteristics of the epithelial tissue organization and the changes occurring during the initiation and progression of carcinomas. It reviews similarities across nine types of epithelial neoplasms, focusing on their association with risk factors and shared molecular, cellular, and histological processes underlying precursor lesions. Additionally, the chapter explores events driving progression to high-grade carcinomas, emphasizing recent studies on the role of cellular senescence and epithelial to mesenchymal transition in dynamic alterations from early stages to advanced poorly differentiated disease. The discussion highlights discoveries enhancing our understanding of epithelial degeneration, malignant transformation, and the development of resistance to anticancer therapies. The convergence of these findings suggests a pattern, that may facilitate the identification of general principles crucial for advancing comprehension, prevention, and treatment strategies for the disease.