Nanobots can be considered as the infantry of precision medicine. They're able to carry drugs to specific cells, hammer (literally!) their way into cells, and deliver their payload right where it hurts.

These tiny robots aren't (usually) miniaturised versions of industrial robots - as things work very different at the cellular level and in the blood that they travel in. Their movement is more akin to bacteria with wriggling tails or spinning corkscrews, either powered by sugar in the body or by magnetic fields that help guide them to their target. The smallest nanobots may be made of DNA that is formed into a cage-like structure containing a pharmaceutical package that is release when the target is reached.

The larger (relatively, they're still tiny!) nanobots have micro-legs to help them move crawl along organs inside the body, or contain cameras and sensors to transmit detailed physiological information back to your doctor to help take the guess work out of diagnosis.

Many futurists predict that before we're halfway into the 21st century we will be injecting ourselves with thousands of nanobots that patrol our bodies keeping an eye out for pathogens and diseases and then swarming together to defend the body against damage.