There was scientific evidence in the late twentieth century that whey had biological, nutritional and technological value. In the past, whey was considered as a waste byproduct. Nowadays, there is growing recognition that it is a valuable raw material that can be exploited in various industries. Protein components and elements related to biological functions are present in large quantities in whey, making them the most nutritionally significant part. They consist of heat-sensitive fractions like β -lactoglobulin (β-LG), α-lactalbumin (α-LA), blood serum albumin, and immunoglobulin, as well as heat-stable proteose-peptone. Other whey components, such as lactoferrin and various enzymes like lysozyme, oxidoreductases, phosphatases, lactoperoxidase, lipolytic enzymes, and proteinases, also exist. These components play a crucial role in the human immune response system. At present, extensive research is being conducted on peptides derived from whey proteins. Bioactive peptides can be easily generated through enzymatic hydrolysis, fermentation, and gastrointestinal digestion. These bioactive peptides serve as signaling molecules and have diverse physiological impacts on the immune, digestive, cardiovascular, and nervous systems once released. Dairy-derived bioactive peptides are linked to a broad spectrum of biological actions, such as immunomodulation, antimicrobial activity, antihypertensive effects, antioxidant properties, opioid characteristics, and anti-obesity functions. The development of probiotic whey beverages has been receiving attention recently because of their beneficial effects. Whey is an excellent medium for growing probiotic bacteria of the Lactobacillus, Bifidobacterium, Propionibacterium genera and other good bacteria. These microorganisms impart unique flavor profiles and textures to dairy products making it functional food. Whey flavor is affected by many factors like the quality of the milk used, the type of cheese made, how whey is handled after curd draining and other factors. As a result, we have different chemical compositions of whey. During cheese making, lactic acid bacteria, which are added to milk, are responsible for producing aroma volatile compounds such as aldehydes, ketones, lactones, sulfur compounds and other compounds in whey. The aroma of liquid whey may be influenced by a variety of volatile acids with short chains and contribute to the overall flavor of whey. This chapter summarizes the literature on the characteristics, bioactive properties, and factors influencing the viability and flavor of sweet and acid whey. Our focus will be on whey’s potential as a source of bioactive peptides, probiotics, organic acids, aromatic compounds and enzymes.