In fact, there is a concept of "whiteness" when it comes to white shirts. The color white has a range of shades. Many dress shirts sold at mass-market suit retailers have a bluish tint. While this looks clean and sharp, it loses the natural hue of the cotton. This is because that shade is created by chemicals known as fluorescent whitening agents.
Shuttle notes shirts aim for a natural level of whiteness without using any fluorescent whitening agents. They fit perfectly with both jeans and jacket styles.