Nanopores enable the sensing of individual molecules based on the temporary blockades in ionic pore current. Initially conducted a decade ago with a biological protein pore, electrical recordings are now routinely performed with synthetic pores sculptured into polymeric and inorganic membranes. Assisted by channel engineering, the range of analytes has been expanded from nucleic acids to peptides, proteins, organic polymers, and small molecules. Apart from being an attractive analytical approach, nanopore recording has developed into a general platform technology with which it is possible to examine the biophysics, physicochemistry, and chemistry of individual molecules. Nanopores can also be exploited for separation technologies and nanofluidics due to their ability to control the flow of solvated ions. The combined use with atomic force and fluorescence microscopy is extending the versatility of nanopores for single-molecule research.