“Human augmentation” means increasing and enhancing our “natural” abilities (or overcoming our limitations) through external means i.e. using tools and techniques which augment our natural abilities to provide new “capabilities”. Individuals will each have different capabilities, as each brings different natural abilities and selects different tools.
Capability augmentation is nothing new to humanity – we've been augmented since the day a proto-human picked up a rock and enhanced his skull-cracking capability. These days, augmented humans can fly, communicate across vast distances, carry enormous loads, even survive in the vacuum of space: it all depends on the tool being used.
As we head towards the 22nd century, the tools used may become more and more part of our bodies – pacemakers, artificial organs, hearing-aids all approach “tools as body-parts” in their own way. Indeed, just as contact lenses and glasses allow poor-sighted humans to see (almost) as well as genetically well-sighted individuals, laser surgery can actually modify our eyes into tools that allow us to see even better than the unenhanced.
When we hear of “human augmentation”, we are most often talking about this kind of tool-integration – roboticised limbs, cybernetic eyes, cochlear implants. Futurists imagine a world where what we are born with is just the beginning, as we augment ourselves with new and wonderful capabilities until we are no longer recognisable as the born-species – this is called transhumanism.
However, there are other less-visible but no less interesting types of augmentation which are already greatly affecting our lives and our culture: