Adipose or fat tissue is one of the largest endocrine organs in the body, and can range from 4% to >40% of total body composition. Fat is the active site for energy storage, primarily in the form of white adipose tissue (WAT), and also plays a critical role in regulation of whole-body energy homeostasis through non-shivering thermogenesis, primarily in brown adipose tissue (BAT). Recent evidence suggests that beige adipocytes are an inducible form of thermogenic adipocytes that are identified in distinct fat depots throughout the body. Adipose tissue dysfunction is strongly associated with several metabolic diseases including obesity, diabetes, dyslipidemia, and steatotic liver diseases. The mechanisms underlying adipose tissue dysfunction include adipocyte hypertrophy and hyperplasia, inflammation, impaired extracellular remodeling, and fibrosis. The functional pleiotropies of adipose tissue rely on its ability to synthesize and release a large variety of hormones, cytokines, and growth factors, collectively known as adipokines. Moreover, adipose progenitor cells, adipocytes, immune cells, and other cell types in adipose tissue promote metabolically healthy tissue remodeling. Thus, adipose tissue represents a dynamic endocrine and metabolic organ that contributes to health and disease.