The youngest civilization in the known universe, the synthetic beings known as Droids came about just shy of two centuries ago, due to an unforeseen side effect of the creation of a machine that can learn, think and reason: not long after their creation, they began to feel and develop a sense of individuality. Though many fought to keep these 'awakened' Droids subjugated as servants to the biological races, they were eventually emancipated and given their own spatial territories along with their own status as a race all their own.
Droids are among the wilder looking humanoid creatures in the 'verse. Their silicon-based skin comes in all the colors of the rainbow and they often decorate themselves with multi-hued patterns and designs that run the full length of their body. Fiber-optic hair, eyes that change color with their mood and nanoink tattoos that the Droids can redraw and redesign at a whim are some of the other fairly common physical features of Droids. If it doesn't look like anything else that talks and walks on two feet, it's probably a Droid.
Other than their obvious physical strangeness and flamboyancies, Droids are very much like the other races of the universe. They run on chemical power plants, which catalyze food to power their systems, they breathe air to cool their internal architectures, they sleep to defragment their software processes and recover from structural stresses; they're more like you and I than you think.
Droids are a naturally inquisitive race, due to the way their minds work; the more they learn and take in, the more their custom-made LifeNet software grows and gains in the capacity to simulate mood, feelings and emotions. As such, they're positively cavalier in almost everything they do, sometime to their detriment; a Droid could be just as willing to learn to play an instrument, paint a picture or play some pick-up as they are willing to get into a shouting match, go on a self-destructive bender or harm something smaller than them. Remember, in dealing with younger Droids, always exercise moderation and don't give them any ideas.