Most counted cross stitch projects are worked on evenweave fabrics made especially for counted thread embroidery. These fabrics have vertical and horizontal threads of uniform thickness and spacing.
Aida cloth is a favorite of beginning stitchers because its weave forms distinctive squares in the fabric, which makes placing stitches easy.
To determine a fabric's thread count, count the number of threads per inch of fabric.
In addition to evenweave fabrics, many stitchers enjoy using waste canvas and perforated paper. Waste canvas is basted to clothing or other fabric, forming a grid for stitching which is later removed. Perforated paper has holes evenly spaced for 14 stitches per inch.