The paper discusses the importance of viability for the probiotic functionality of *Bifidobacterium* species, particularly in dairy-based probiotic foods like yogurt. It highlights the challenges in maintaining *Bifidobacterium* viability during manufacturing and shelf life, influenced by various stress factors such as acid, osmotic, heat, oxidative, and cold stress. The paper reviews stress response mechanisms in *Bifidobacterium* spp., including the production of stress proteins, osmolytes, and antioxidants. It also explores strategies for viability retention, such as process modifications (de-aeration, electroreduction, high-pressure homogenization), stress adaptation, microencapsulation, and the use of protective agents. Additionally, the paper examines methods for accurate viability determination, including culture-based techniques and flow cytometry, noting the limitations of current methods and the need for more efficient and species-specific approaches.The paper discusses the importance of viability for the probiotic functionality of *Bifidobacterium* species, particularly in dairy-based probiotic foods like yogurt. It highlights the challenges in maintaining *Bifidobacterium* viability during manufacturing and shelf life, influenced by various stress factors such as acid, osmotic, heat, oxidative, and cold stress. The paper reviews stress response mechanisms in *Bifidobacterium* spp., including the production of stress proteins, osmolytes, and antioxidants. It also explores strategies for viability retention, such as process modifications (de-aeration, electroreduction, high-pressure homogenization), stress adaptation, microencapsulation, and the use of protective agents. Additionally, the paper examines methods for accurate viability determination, including culture-based techniques and flow cytometry, noting the limitations of current methods and the need for more efficient and species-specific approaches.