This chapter reviews the main concepts of imaging, spectroscopy, and manipulation by scanning tunneling microscopy, an experimental technique that, since its invention in 1981, has strongly changed surface science and has proven to be much more than an imaging technique. After a historical introduction, we will describe the working principle of scanning tunneling microscopy and the role of tunneling electrons for performing local electron spectroscopy. In the second part of the chapter, we present the different possible manipulation methods that allow us to build structures atom by atom or molecule by molecule. Manipulation with the tip of a scanning tunneling microscope allows us to obtain precise local information about mechanical properties and interactions, and opens the way to applications in atomic-scale technologies.