Root caries is a multifactorial disease that primarily affects the exposed root surfaces of teeth following gingival recession and the loss of periodontal attachment. Unlike the coronal caries, root caries involves the softer tissues of cementum and dentin, which are more prone to demineralization due to the lower mineral content and increased organic content. The rising prevalence of root caries, particularly among the aging population is attributed to factors such as poor oral hygiene, reduced salivary flow, systemic health conditions, and limited dexterity, which all hinder effective plaque control. The microbial flora in root caries is distinct, involving not only commonly known cariogenic species like Streptococcus mutans and Lactobacillus but also organisms such as Actinomyces, Olsenella, and Atopobium. Clinically, the lesions may range from yellowish or light brown in active cases to darker brown or black in arrested ones, with varying degrees of cavitation and texture. Accurate diagnosis of root caries remains a clinical challenge. This review focuses on the etiology, microbial aspects, clinical presentation, and most importantly, the evolving diagnostic modalities for root caries from traditional visual and tactile assessment using a dental explorer to advancements in caries detection with the help of laser fluorescence, fiber-optic transillumination based imaging systems. Integrating these diagnostic modalities into routine practice can improve early intervention, guide minimally invasive treatments, and ultimately enhance the long-term oral health outcomes.