A DNA walker is a class of nucleic acid nanomachines where a nucleic acid "walker" is able to move along a nucleic acid "track". The concept of a DNA walker was first defined and named by John H. Reif in 2003.
A nonautonomous DNA walker requires external changes for each step, whereas an autonomous DNA walker progresses without any external changes. Various nonautonomous DNA walkers were developed, for example Shin   controlled the motion of DNA walker by using control strands which needed to be manually added in a specific order according to the template's sequence in order to get the desired path of motion.
In 2004 the first autonomous DNA walker, which did not require external changes for each step,  was experimentally demonstrated by the Reif group. 
DNA walkers have functional properties such as a range of motion extending from linear to 2 and 3-dimensional, the ability to pick up and drop off molecular cargo, performing DNA-templated synthesis, and increased velocity of motion. DNA walkers have potential applications ranging from nanomedicine to nanorobotics. Many different fuel options have been studied including DNA hybridization, hydrolysis of DNA or ATP, and light. The DNA walker's function is similar to that of the proteins dynein and kinesin.