The term ceramic tile is often used generically for porcelain as well as ceramic tile. The differences in their ingredients, manufacturing process’ and installations differ only slightly, but enough to make them two similar but completely different materials. Ceramic tile is the oldest, longest lasting flooring material known to man. In fact, ceramic mosaic tiles were in use since 2000 BC and were discovered not so long ago on the floors of homes in Pompeii, having survived the eruption of Mount Vesuvius in the year 79 AD! The very first ceramic tiles were made of clay, flint and flux, shaped by hand and dried in the sun. Today, ceramic tile is still made from the same two primary ingredients – clay and water. Although tile making was revolutionized during the 1840’s via new methods and the addition of better materials, there have been no man made efforts able to change or improve the tile setting process. It remains a hand operated, labor intensive process, to this day. The clay is first mined, then ground and blended into a fine powder and then pressed together mechanically to form the body of the tile. Next, the tile is dried to reduce the moisture content, then, in most cases; the surface is coated with glaze. The glaze is permanently fused to the tile by firing in a kiln at 2000 ° F. This glaze comes in a multitude of colors and its purpose is not only decorative but also makes the tile harder, increases its strength, durability and water resistance. The strength of each tile is graded into one of five categories. Strength is determined by its density, which in turn determines its suitability to a specific area. Higher density tile has fewer air pockets so it absorbs less water, making it stronger, more durable and less likely to crack in colder temperatures. Almost all tile will absorb some moisture, any where from .01% to 7% of its weight. Any tile with a rating of 1 is for light traffic, such as a residential bathroom or anywhere that shoes are not usually worn. A rating of 2 is for moderate traffic in a residential home. 3 is ideal for a residential kitchen, an entry way or stairs. 4 is the most commonly available quality as it can be used anywhere in your home and in most commercial environments. 5 can be used in all areas including the exterior of your home such as a walkway or swimming pool.