To tie dye, first, fold or crumple fabric and tie it with string or rubber bands. Then, dip the fabric in buckets of dye, or apply the dye with squirt bottles. The folds and ties act as a resist, preventing the dye from saturating the fabric evenly.

The folds of the fabric and the ties securing them act as a resistance to the dye. It prevents the dye from staining those areas, leaving them white (or whatever the original color of the fabric was) and creating different patterns. Because of that, the way you fold and tie your fabric is important!