An antenna is a device capable of effectively transmitting, picking up, and redirecting electromagnetic radiation. Typically, antennas are macroscopic devices operating in the radio and microwave range. However, there are similar optical devices (Fig. 1). The wavelengths of visible light amount to several hundred nanometers. As a consequence, optical antennas are, by necessity, nanosized devices. Optical nanoantennas, which can focus, direct, and effectively transmit light, have a wide range of applications, including information transmission over optical channels, photodetection, microscopy, biomedical technology, and even speeding up chemical reactions.