Solid tumors are made up of multiple subclonal populations of tumor cells, which compete under selective pressures leading to the emergence of dominant subclones that replicate and form the molecular landscape of solid tumors. The genomic landscape of tumors is heterogeneous and longitudinal sampling is essential for precision medicine. This can be achieved with sampling tumor components, such as circulating cell-free DNA (ctDNA), tumor-derived RNA and circulating tumor cells (CTCs), via patients’ blood samples, a process known as ‘liquid biopsy’. The application of liquid biopsies has developed at a high rate over the last 5 years, with over 60 clinical trials and more than 20,000 patients over 11 cancer types evaluated. Exploiting approaches in liquid biopsy can provide a comprehensive overview of tumor characteristics, including aggressiveness and the overall molecular landscape to improve clinical outcomes for patients with cancer. This collection of recent high-quality full-text articles from Springer Nature provides some of the most impactful recent work in this burgeoning area.