It means allowing feet to act as nature intended and free of outside influence. Instead of putting our feet in restrictive, inflexible shoes and expecting them to do all of the work for us, it's relying on our own biology to do the job it was made to do. The most pure form of this is barefoot -- wearing nothing on our feet at all. This allows for full flexibility, greater strength, and total sensation of the ground below us. There are also various forms of primal footwear that generally allow feet to function naturally. These shoes and sandals are light, flexible, have a very thin sole with no arch support or cushioning and allow feet to breathe well while maintaining a natural walking gait. The only downfall to primal footwear is that there is still no sensory feedback from the ground.