Nanotechnology or "nanotech" is the manipulation of matter on an atomic, molecular and supramolecular scale.
It is giving humans powers that previously could only be attributed to mythical, god-like creatures. These include for example:
holding your breath at the bottom of a pool for an hour (via red-blood-cell-replacing respirocytes)
allowing for reverse aging (via nanobots called chromallocytes that would insert fresh chromosomal material into your cells)
ending global warming (via solar-powered diamond trees that transform carbon dioxide into oxygen)
making materials that are 50 times stronger than steel for the same weight