What type of tile is characterized as unglazed and impervious?

Porcelain tile is characterized as unglazed and impervious, making it a highly durable option for a variety of applications. It is made from a denser, finer clay compared to standard ceramic tiles and is fired at higher temperatures, leading to a very low porosity. This quality not only makes porcelain tile impervious to water and stain absorption but also enhances its resistance to wear and scratches, which is why it is often recommended for high-traffic areas and environments exposed to moisture.

In contrast, while ceramic tiles can also be unglazed, they do not typically have the same level of density and impervious quality as porcelain tiles. Vinyl tiles, on the other hand, are a completely different category made from synthetic materials and lack the characteristics associated with natural stone or clay tiles. Glass tiles are usually glazed, making them more susceptible to scratching and less impervious compared to porcelain. Thus, the defining features of porcelain tile clearly identify it as the correct answer.