“Anyone, therefore, who does baking should use flour which is well-ground from wheat… from this, he should separate the bran and the inferior flour with a very fine flour sieve, then put the flour, with warm water and some salt, on a baker’s table closed in at the sides, as the people at Ferrara in Italy are accustomed to do. If you live in damp places and a bit of leaven is used, [the baker], with help from his associates, kneads to that consistency at which bread can be made fairly easily. Let the baker be careful not to put in too much or too little leaven, for, from the former, bread can acquire a sour taste, and, from the latter, it can become too heavy to digest and too unhealthy, since it binds the bowels. Bread should be well-baked in an oven and not used the same day, nor is it especially nourishing when made from very fresh wheat and if it is digested slowly.”
The late 15th century recipe book contains a narrative on how bread is made. Note that there are no specific amounts of ingredients, just someone’s experience written down for others to follow. From the description above, this Italian recipe provides a good overview on how good quality bread would be made during the era.
Bread has the advantage of being the food staple for most of history and can be found in almost all societies in one form or another, today and in our past. As described above, the bread consists of flour, water, some salt and a leavening (as is the desired result is a raised loaf). The variety of breads is provided through the quantity, quality and types of each ingredient. 
This then provided that the in that the most expensive ingredients (whiter, more finely ground and sifted flour) went to those that could afford them and thus a lighter color of bread was the premium and the least expensive ingredients (whole grains that were not milled at all) for the poorest of townsfolk.
From these two extremes, we are able to see the picture of bread as displayed here today. The whiter, finer flour provided the most expensive bread and the darker; more course flour was the less expensive yet still allowed the middle class their heavy bread. Those that could not afford to have their grain milled ate the grains whole after boiling in water and created porridge or added vegetables for a pottage.
By the 15th century, the milling process was able to produce wheat into flour then sifted the stone ground flour through linen and only the finest flour particles went into the finest bread – served to the highest status Lords and Ladies as part of the meal. The remaining wheat germ was not as highly prized and was added to flour for people other than that of the Lords and Ladies.
A sourdough was used to provide fermentation from the flour and water mixture. This pulled the wild yeast out of the air which created carbon dioxide and allowed air to form within the loaf. This was done through a starter.
Modern yeast cultures were separated out and packaged beginning in the late 1800s. The leavening for each of the breads was a sourdough base. I started this a few years ago using only water and stone ground, whole wheat flour. It is fed only stone ground flour and water a week before it is needed. Sourdough needs longer to raise than a modern yeast. Once the flour, water, leavening and other ingredients were mixed, each bread sat overnight to raise the first time, then was formed into shapes and again left overnight to raise.
The finest and whitest of the flours were used to create the eating bread for this class of people. There are two types of bread: manchettes and trenchers.
These raised white rolls were a highly prized presentation of wealth. To get the white flour, I sifted the stone ground whole wheat with a very fine sieve to separate the bran from the fine flour. Also, honey was added to add a sweetener to the bread. At the time honey was less expensive than sugar as it was not imported.
Made of heavy whole wheat sourdough, this 4 day-old bread was used to provide a personal cutting board for each person.
This heavy loaf contains a combination of dark rye, wheat germ and some flour. The wheat germ was derived from the sifting of stone ground whole wheat flour to leave the white for the upper class manchettes. Since this was designed for the middle class family, salt could be afforded by the middle class.
As discussed earlier, those that could not afford to have their grain milled ate the grain whole with vegetables as their daily food staple. Grains used were local grains. Some areas were more prevalent with barley, others wheat, and others rye. Types of vegetables added were root based vegetables including carrots (not the modern orange, but purple and white are some examples), turnips, and other hearty root vegetables.
 De honesta voluptate, book I.14, Platina, Venice L. De Aguila, 1475
 The Tudor Housewife, Alison Sim, p. 62
 Daily Life in Medieval Time, Frances & Joseph Gies, p. 165
 The Tudor Housewife, Alison Sim, p. 62
 The Boke of Keruynge, Wynkyn de Worde – introduction, p. 7
 Private Life in the 15th Century