Liquid biopsies represent a groundbreaking, non-invasive approach to cancer diagnosis and monitoring. By analyzing circulating tumor DNA (ctDNA), RNA, and exosomes in blood, these tests detect genetic mutations and tumor-specific biomarkers. Liquid biopsies offer real-time insights into tumor dynamics, aiding in early detection, treatment selection, and monitoring resistance. Their applications span multiple cancer types, including solid and hematologic malignancies. Emerging technologies, such as single-cell analysis and nanoparticle-based detection, further enhance sensitivity and specificity. Although challenges like standardization and cost remain, ongoing research continues to refine liquid biopsy methodologies, paving the way for widespread clinical adoption in precision oncology.