This chapter describes the technical details of three single-molecule techniques that are utilized for the study of single chromatin fibers including the atomic force microscope (AFM), optical tweezers (OT), and magnetic tweezers (MT). The AFM produces digital topographical images of samples deposited on flat surfaces by raster-scanning the surface with a sharp tip mounted on the back of a flexible cantilever. Atoms on the tip interact with atoms on the surface, causing the cantilever to deflect upwards or downwards, depending on whether the tip-sample interaction is repulsive or attractive. The deflections of the cantilever are registered by a laser beam reflected off the back of the cantilever to produce a topographical image of the sample. OT technique uses for manipulating single molecules based on the interaction of light with matter. Light can exert forces on small beads of certain optical properties in such a way that the bead is kept suspended at a point close to the waist of a laser beam that is focused with an objective. In the MT, the macromolecule is attached between a surface and a magnetic bead. Manipulation of an external magnetic field can be used to apply stretching force to the tethered molecule, and/or to induce precisely known levels of supercoiling: stretching is achieved by changing the distance between the external magnet(s) and the cuvette, while supercoiling is introduced by rotating the external magnetic field either clockwise or counterclockwise.