Gold nanoparticles are one of the most popular and extensively researched type of nanoparticle. Many characterization techniques exist that provide a wealth of information. Nanoparticle Tracking Analysis is a powerful complementary technique for high resolution analysis of particle size distributions and concentration measurement. In this application note, example sample types are discussed with measurement examples to show the strength of the NTA technique. NTA offers a unique capability to characterize colloidal samples by directly visualizing nanoscale particles in suspension (10nm to 2000nm) with high-resolution, in real-time, and with minimal sample preparation.