In shopping for ceramic tiles I have heard the term RECTIFIED TILES.  Why would I want these?

Rectified tiles means the tile dimensions in width and length are more precise than regular tiles as they are cut after the firing process.  If you are looking to use larger tiles or want a grout width of 1/8" or less, you would want to use a rectified tile.  The trend is for less grout showing so using a rectified tile that is uniform in dimensions makes this possible.  Otherwise a normal tile will require much larger grout lines to make u for the differences in tile sizes from one tile to another.  As tiles get larger it is important to have uniformity in dimensions.  Rectification of the tiles does not affect the thickness.