What does Bleaching mean?
The process of applying bleach to yarn or fabric to adjust the color and remove and natural or artificial impurities from fabric as well as used to adjust the fades of denim.
Heddels explains Bleaching
Bleaching refers to the process of lightening an item by exposure to sunlight or chemicals. Historians have found examples of bleached linens in Egypt dating back to 5000 BC, though many speculate that the process is even older. Bleaching works by breaking down the chemical bonds between the dye and fiber and is commonly used for lightening teeth, hair, and, in our case, fabric. With jeans, the application method(s) used varies according to the look desired and can include sponging, soaking, dabbing, splattering, or spraying.
Here is an example of bleached denim: