Freckles are clusters of pigment cells or melanized cells easily visible on fair complexion and are seen as flat brown spots or pigmented spots which are equally distributed and are relatively uniform in size and color, commonly found on sun exposed areas such as face, neck, upper back, arms and shoulders. Freckles do not have an increased number of melanocytes but instead have melanocytes that overproduce melanin pigment changing the coloration of the outer skin cells or keratinocytes.
These get darker with more sun exposure as uv rays activates melanocytes to increase melanin production.
These are thought to occur mostly because of genetic predisposition and is prominently visible in light coloured skin.

How does laser treatment helps in removing freckles?
1064nm q switch neodymium laser is used to remove freckles. Laser treatment of pigmented lesions is based on the principle of selective photothemolysis , which states that a laser light must emit a wavelength that is specific and well absorbed by the particular chromophore being targeted. Regular sessions can lighten or eradicate these lesions.
Usually there is slight scabbing for a week with this laser for brown spot lightening.