Grout Sealer, in general, clogs the pores of the grout to help keep the grout from absorbing anything that will discolor it.
There are two options for this process: a clear sealer which protects the grout or a color stain sealer which both corrects discoloration and seals.
Color stain (also known as Grout Colorant or Grout Dye) can be used to re-color, refresh, and seal your grout. Applying color stain to your grout revitalizes it making it one cohesive color.
Grout Stain is an excellent alternative to re-grouting your entire tile floor. It eliminates the mess and labor of removing your old grout, as well as the chance of damaging your floor.