The ability of proteins to locate specific target sequences or structures among a vast excess of nonspecific DNA is a fundamental property that affects virtually all aspects of biology. Despite this importance, experimental methods have lagged behind the establishment of theoretical principles describing potential target location mechanisms. However, recent advances in single-molecule detection now allow direct visual observation of proteins diffusing along DNA. Here we present an overview of these new observations and discuss the advantages, limitations and future prospects for imaging the motion of proteins along DNA.