Macro fiber
Synthetic or steel fibers roughly one to two inches long, dosed into concrete to provide post-crack load transfer. They can replace wire mesh in many slabs on grade.
What does macro fiber mean?
Once a crack forms, macro fibers bridge it and carry force across, which is the same service function wire mesh performs. Because they are distributed throughout the concrete, they cannot be mispositioned the way mesh routinely is. They do not replace structural reinforcement designed by an engineer, and high dosages affect finishing.
In practice
Many residential and commercial slab specs now allow fiber in place of mesh, which removes a whole trade and a whole failure mode from the pour.