Inspired by watching track athletes training barefoot, Nike innovation manager Tobie Hatfield (the same guy that created the Nike Presto) developed the Nike Free technology.
The first Nike Free 5.0 was launched in 2005 and several improved versions of the Nike Free 5.0 have been released since then. The numbering system indicates the cushioning level of the shoe, with Free 3.0 being the least cushioned and Free 7.0 being the most cushioned model.