The liver lobule, the functional unit of the organ, is composed of a portal triad, a capillary network lined by hepatocytes, and a central vein. Zone 1 represents the periportal region, consisting of the portal triad that is made up of the hepatic artery, the hepatic portal vein, and the bile duct. Zone 2 represents the interzonal region, and Zone 3 consists of the pericentral region. The cellular composition of the liver can be categorized as parenchymal cells (hepatocytes) and non-parenchymal cells, including cholangiocytes, hepatic stellate cells, endothelial cells, and immune cells. Almost all types of immune cells can be found in the liver tissue. These immune cells include phagocytes (macrophages, DCs, and neutrophils) and lymphocytes (innate lymphoid cells, T cells, and B cells). Many of these populations currently lack confirmation and consensus regarding their location and definitive frequencies in the liver, thus most of their distribution remains speculative. Abbreviations: DC, dendritic cell; ILC, innate lymphoid cell (type 1, 2, and 3); MAIT, mucosal associated invariant T cell; NK cell, natural killer cell; NKT, natural killer T cell; Th1, type 1 helper T cell; Th2, type 2 helper T cell; Th17, type 17 helper T cell; Th22, type 22 helper T cell; Treg, regulatory T cell.