With the advent of technologies such as augmented/virtual reality (AR/VR) that are moving towards displays with high efficiency, small size, and ultrahigh resolution, the development of optoelectronic devices with scales on the order of a few microns or even smaller has attracted considerable interest. In this review article we provide an overview of some of the recent developments of visible micron-scale light emitting diodes (LEDs). The major challenges of higher surface recombination for smaller size devices, the difficulty in attaining longer emission wavelengths, and the complexity of integrating individual, full color devices into a display are discussed, along with techniques developed to address them. We then present recent work on bottom-up nanostructure-based sub-micron LEDs, highlighting their unique advantages, recent developments, and promising potential. Finally, we present perspectives for future development of micro-LEDs for higher efficiencies, better color output and more efficient integration.