The 21st century (2001–2100 A.D. in the Gregorian Calendar) saw the creation of Artificial Intelligence and the Machines, the invention of the hoverpad, and the start of the Second Renaissance. According to Agent Smith, the early 21st century was considered "the peak of your[human] civilization."
The Resistance of the Seventh Matrix believed that humanity created (in Morpheus' words "gave birth to") a single Artificial Intelligence during the early part of the 21st century. This A.I. then in turn created ("spawned") the sentient Machines and Programs.
For a time, there was peace and harmony as Machines were programmed to serve humans, cleaning households and performing in other hazardous working conditions Humans. As a result, the humans became increasingly lazy and complacent while the machines became more and more advanced with different models of each decade or so. It eventually got to a point where the Machines somehow started to gain sentience and a sense of self-preservation.
Hoverpad technology seems to have been invented by 2026 at the latest, when the oldest known Hovercraft to survive to the time of the Seventh Matrix, the Pequod, was built in the United States of America. This was followed by the Nebuchadnezzar (2069), and the Osiris (2079), with the Logos, Vigilant and Mjolnir being built in the early 22nd century.