This is a great question! Most people who have encountered liquid bleach or bleaching powder know that bleach will remove colors (also called pigments) from fabrics and other materials as well, as kill bacteria and other microorganisms; however, not everyone knows how this process works, or, to put it more technically, the mechanism through which bleach accomplishes these useful tasks.

To best answer this question, we're going to have to think about some chemistry. First of all, pigments are made of organic molecules containing segments called "chromophores" which, when illuminated with white light, will absorb some of the colors and reflect other colors. The colors that are reflected are the colors that we perceive when we view an object with our naked eyes. The properties and chemical structures of chromophores that let them absorb light are very specific, and tend to be very "chemically active," or able to participate in chemical reactions very easily.

Both liquid bleach (a solution of sodium hypochlorite, NaClO) and bleach powder (solid calcium hypochlorite, Ca(ClO)₂) are also very chemically active and work by reacting with chromophores in pigments and destroying the structures that allow the chromophores to absorb light. If the chromophores can't absorb light anymore, then they reflect all of the colors of white light and the material appears white to our eyes.

Bleach works somewhat similarly when it kills microorganisms. Bleach either unravels the delicate protein structures that bacteria or other pathogens use to live or disrupts the cell membranes of the bacteria, causing them to pop, quite like a balloon!

Thanks for being so curious! I hope my answer helped you better understand how bleach works. Keep the questions coming!