The purpose of kneading dough is to create a strong gluten structure for foods such as biscuits and breads. Production of carbon dioxide via chemical or biological means expands the elastic gluten structure forming the finished product.
Flour contains two proteins called gliadin and glutenin. These two proteins combine upon manipulation in the presence of water to form gluten a protein that combines the stick character of gliadin with the elastic qualities of glutenen. The key to successful kneading is to stretch (push) about 1/3 of the dough away from your body then to fold (pull) the dough back upon itself. Rotate the dough slightly and repeat until gluten structure is in place.