Salivary diagnostics is considered to be a promising method for the early diagnosis, prognosis, and post-therapy monitoring. Saliva is a hypotonic solution that consists of salivary acini, gingival crevicular fluid, and oral mucosal exudates. It is primarily secreted by the salivary glands, with the major glands being the parotid glands, submandibular glands, and sublingual glands. Salivary glands with high permeability are surrounded by numerous capillaries, blood, and acini, which allows for the exchange of molecules between the blood circulation and saliva. According to recent research, whole saliva is a complex mixture that consists of secretions from the major and minor salivary glands, mucosal transudations, gingival crevicular fluid, serum and blood derivatives from oral wounds, desquamated epithelial cells, expectorated bronchial and nasal secretions, bacteria and bacterial products, viruses and fungi, and other cellular components, as well as food debris. Thus, saliva contains various hormones, proteins, enzymes, antibodies, antimicrobial constituents, and cytokines that can provide a wealth of information for diagnostic purposes. Saliva is considered to be an excellent source of sampling due to several advantages over serum and tissues. One of the most significant advantages is that it can be collected noninvasively, making it a more comfortable and less painful method for patients. Additionally, saliva samples require smaller aliquots, are cost-effective, and can be easily stored and transported.