When shopping for ceramic tile keep in mind that not all tiles are made equal and that not all tiles are used equally either. Buying a tile in the grade that matches the use of the ceramic tile in your home will guarantee that you do not spend unnecessary money on super strong tiles that won't even get a chance to flex their muscles in your lightly used guest bathroom, for example. Floor tile should be stronger than wall tile and heavily used areas like kitchens and bathroom should have appropriate kitchen floor tile and bathroom floor tile to wear well. Below are the classifications used for ceramic tile.
Grade 0 (PEI I): Decorative tile.
Grade 1 (PEI I): Residential and commercial wall tile or floor tile to be used by barefoot traffic.
Grade 2 (PEI II): Residential and commercial wall tile or floor tile to be used by soft soled traffic.
Grade 3 (PEI III): Suitable for all residential floors and light use commercial floors.
Grade 4 (PEI IV): Suitable for all residential floors and light industrial floors with moderate soiling.
Grade 5 (PEI V): Suitable for all residential floors as well as heavy traffic commercial and industrial areas with abrasive dirt.