Abstract: According to the GLOBOCAN 2020 data from WHO, nearly 10 million deaths took place due to cancer thus, cancer became a leading cause of death all over the world. The most common cancer are breast cancer, lung cancer, colon cancer, prostate cancer, and pancreatic cancer. In the last few decades, Tissue Biopsy was considered the major approach to finding a confirmed diagnosis of particular cancer but due to the invasive process, it has become difficult for the clinician to ask for frequent tissue biopsies for the monitoring targeted treatment of the patients and thus clinicians generally assume the potency of the drugs without doing any biopsy analysis and thus there is an increase in the mortality of cancer patients. However, the liquid biopsy technique has changed this protocol of such treatment and greatly revolutionized the field of Clinical Oncology. Liquid biopsy ensures better-targeted treatment and many times help to give a complete cure. Liquid Biopsy is a non-invasive standard procedure to identify and prognose the tumor markers from circulating blood samples. It also offers the ease of sampling continuous screening, monitoring devices, therapeutic regimens, etc. Liquid Biopsy is composed of several components such as Circulating Tumor Cells (CTCs), free Circulating Tumor DNA (ctDNA), exosomes, vesicles, and platelets. The liquid biopsy includes body fluids such as blood, saliva, plasma, cerebrospinal fluid, and urine. Circulating Tumor DNA (ctDNA) in the blood sample of metastatic cancer patients has become the most critical technology to evaluate the progression of metastasis and give a precise treatment for many cancers. ctDNA analysis provides insight into the molecular profiling and biological characteristics of several tumors. This review is mainly aimed at highlighting the important technological development in ctDNA analysis and also to provide the significance of it in monitoring metastatic cancers and providing the best treatment to cure cancer.