Tie Dye is a method of dyeing fabric after tying strings around it, creating bright swirls of color. It became fashionable in the US during the 60s and 70s and was popularized by musicians such as John Sebastian, Janis Joplin, The Grateful Dead and Joe Cocker. [source : this topic’s Wiki page]
There are several kinds of patterns you can create with tie-dye: [I took these from http://www.howtotiedye.org and added some corrections so it made sense :P]
Knot Tying: This type of tie dye pattern is ideal for light materials and long sleeves. First, carefully twist the fabric from both ends like a rope, tightening it slightly. Then, tie strings or rubber bands onto the fabric to fasten it. You can tie as many knots as you need to on the fabric, depending on your design. This tie dye pattern will give you fine lines.
Pleats: Lay the garment flat and, using your hands, pinch it to create folds on the material. Continue creating these folds until the entire fabric is pleated. You can change the size of the fold to change the design. Fasten the folds several times tightly and knot the strings. This is one of the basic tie dye patterns that can be used for making diamonds, squares, ovals or any symmetrical design.
Spirals: Spiral tie dye patterns are created using your thumb or a fork. Place the fork on the spot that will become the center of the spiral, and rotate it, creating pleats in a spiral pattern all around the outside. Get the loose ends within the circle and flatten the fabric using your palm. It will resemble a pancake. Take rubber bands and slide them over the cloth without disturbing the design. Let the rubber bands meet at the center. You can use various colors and the spiral created on the material looks stunning.
Electric Bunching: Bring together the ends of the fabric in bunches and shape it into a ball. Fasten it well with rubber bands, being careful to retain the shape. Then dye it. This creates the pattern of electric light or lightening-like designs.
Rosettes: Make dots on the fabric as the centers of the rosettes. Gather the dots together and tie them up with strings at the base of the circles. Wrap very well to the tip.
Stripes: To make stripes you must roll the garment loosely and shape it into a tube. You will get vertical stripes on the tube. Tie them at various intervals depending on how close you want the stripes. Using strings, tie several times very tightly. Apply dye by either immersing the garment or squirting colors on it.