Owing to climate and geography, certain regions of the world
produce better or more desirable cotton for sheet fabric.
Following is a brief description of some of the different types of
cotton:

1. Pima cotton is a variety of cotton developed in the southwest US. Pima is an extra-long-staple cotton that was developed from Egyptian cotton. Pima cotton, rivaling the
   quality of Egyptian Cotton, is often used to make high quality sheets.
2. The Nile Valley produces nearly the same breed of cotton as the US. Generally
   regarded as the finest cotton fiber, this cotton is called Egyptian Cotton. The fibers are long, soft, and thick and are used to weave very high quality fabrics. Our Dreamfit 400 Thread Count Sheets are made from fine Egyptian Cotton.
3. “Sateen” cotton fabric can be made from any variety of cotton, and the term “sateen” refers to the type of weave used in making the fabric. With sateen fabric, the weaver stitches four threads over, one thread under, placing the most threads on the surface. This creates an extremely soft cotton fabric with a satin-like finish. Our Sealy Best Fit sheets are made with sateen cotton fabric.

Caution High Thread Count Alert:

Thread count can be tricky, because sometimes cut-rate linen manufacturers exaggerate the thread counts of their products. One way to do this is to twist gossamer thin threads around a central thread to overstate thread count. Be wary if you find an inexpensive set of sheets that claim to be 1000 thread count. If sheets truly are made of good quality 1000 thread count fabric, the price will not be cheap.

Take a look at my post about a sample set of 600 thread count sheets I tried out.