 Recent advancements in plasmonic nanoparticle technology have opened up new possibilities in the areas of energy, catalysis, optics, biotechnology, and medicine. Plasmonic nanoparticles possess strong and tunable optical responses which can be manipulated with external light sources, making them ideal candidates for biomedical applications such as photothermal therapy. However, to fully realize the potential of these particles, further research into their fundamental properties and applications is needed. This report summarizes recent progress in the understanding and application of plasmonic photothermal nanoparticles, focusing on sensing, imaging, therapy, and drug delivery. Future directions of this field are also discussed. This article was authored by Minyu Kim, Younghoon Lee, and Jwamin Nam.