What is the best method for cleaning and maintaining grout for porcelain tile?

The best method for cleaning and maintaining grout for porcelain tile is to regularly clean it with a mixture of water and mild detergent, scrubbing with a brush or sponge. For tougher stains, a mixture of water and vinegar can be effective. Sealing the grout once a year can also help prevent staining and make it easier to clean.