What explains the development of cities and towns during the Middle Ages ? please help me i really need it

The 900s – 1300s was reported to be one of the most notable moments during the medieval ages in Europe. New cities and towns started to develop one after another brought about by the following factors:
* BOOMING POPULATION : The growing population eventually caused new cities and towns to rise in Europe. There were no reported incidence of plagues nor food shortage back then so people were living longer; hence the growth in population.
* TECHNOLOGICAL INNOVATIONS : with the growing population, new and innovative ways in the field of farming & agriculture were introduced. More lands were cultivated, more cereals, oats and other grains were produced. More sustenance and even source of income were provided for the growing communities; hence became one of the factors that enabled cities and towns to develop as well.
* TRADING WAS UP: New roads and forms of transportation were built and this resulted to healthy trading. With the abundance of food being grown in the rural areas, being able to trade and transport food to urban areas allows the growth of towns and cities.