organoids should exhibit essential features, including organ-specific multiple cell types, functions of the organ, and spatially organized structures. The emergence and progression of organoid technologies have resulted from several important discoveries (Figure 1). The formation of actual tissuelike colonies in vitro was firstly observed from a co-culture system of keratinocytes and 3T3 fibroblasts. [4] Self-organization, one of the fundamental aspects of organogenesis, was first observed via two distinct approaches, namely reaggregation and structural patterning of dissociated single cells. [5,6] The establishment of 3D culture methods for the structural organization began with the development of extracellular matrices (ECM).In the late 1980s, Bissell and colleagues observed that a laminin-rich gel could function as a basement membrane to differentiate and morphogenesis of mammary epithelial cells. [7,8] In the 1990s, it was reported that in addition to their primary role in physical support, ECM components could regulate gene expression by interacting with integrin-based focal adhesion pathways. [9] Finally, in 2009, Clevers group reported that embedding single intestinal stem cells in ECM substitute had created crypt-like structures similar to the epithelium of the native intestinal tissues, which were the first organoids. [10] Based on these recognitions, biochemical cues that include the initiation of lineage-specific genetic programs have been incorporated in 3D organoid cultures. Through exposure to morphogens, growth factors, or morphogen inhibitors, multiple research groups rapidly developed various organoid models using embryonic stem cells (ESCs) or adult stem cells (ASCs); these include intestine, [10] stomach, [11] liver, [12] pancreas, [13] prostate, [14] and brain [15] organoids. At the same time, vascularization techniques were devised by several groups to embody microenvironments that are physiologically close to their actual counterparts. Microfluidic systems, [16] endothelial cell-coated modules, [17] and vascular endothelial growth factor delivery systems [18] have been demonstrated as in vitro vasculature systems that can facilitate oxygen or nutrients transport to the inner mass of organoids.In the late 2010s, owing to the accumulated information on mechanisms underlying organogenesis and the remarkable advancements in the fields of biomaterial and bioengineering, the era of "organoid customization" has begun. Customizable hydrogel matrices have been proposed to form intestinal organoids whose internal networks recapitulate the Recent advances in 3D cell culture technology have enabled scientists to generate stem cell derived organoids that recapitulate the structural and functional characteristics of native organs. Current organoid technologies have been striding toward identifying the essential factors for controlling the processes involved in organoid development, including physical cues and biochemical signaling. There is a growing demand for engineering dynamic niches characterized by ...