Probiotics are living microorganisms that improve health when eaten or introduced to the body. They have become an essential aspect of everyone’s life now due to these products growing health benefits. They contain live bacteria that help our gut maintain good gut microflora and keep us healthy. Lactobacillus and Bifidobacterium are the most used probiotic strains. Everyone knows the importance of these products nowadays and has highlighted the parts that a reader must know about these products and how they affect the human body. This review discusses probiotics, dairy-based probiotics, non-dairy based probiotics and their role in therapeutics. This review has also been elaborated on an essential by-product of the dairy industry, i.e., whey, which has many health benefits and highly recommended for people who are in sports and body-building. While analysing the health benefits of probiotic supplements, there is a lot to discuss,i.e. how and where probiotic products work in our body and provide us with different health benefits. The most common way a probiotic performs is by boosting our immune system and fighting diseases. While looking at the market part of probiotic products globally, it is a multibillion-dollar market mostly based in Europe, where people are more health-conscious. The probiotic market has now frowned worldwide and is one of the most profitable markets in the current world.