Fair isle patterns can be knitted by always carrying two colors of yarn throughout the piece, but only working with one color of yarn at a time. The color that is being used can be picked up or dropped when it is needed.
Fair isle knitting is the best technique to use when there are small pieces of a repeating pattern needed to complete the project. It is not ideal for large pieces of color in a project where the yarn should simply be tied onto the main color of the piece. Ageneral rule to follow is that there should be no more than seven stitches of each color when knitting with a fair isle pattern. There should also never be more than two colors per row of knitting.
A fair isle pattern can be added to nearly any knitting design. The actual process of knitting fair isle patterns is the same as standard knitting, but with an extra color that stays behind the knitting pattern the entire time. Fair isle patterns are somewhat difficult and are generally not intended for beginners because the extra yarn that is added to the project can make the various stitches somewhat difficult to keep track of.