The feudal system was a social structure in medieval Europe where the king granted land (fiefs) to nobles (vassals) in exchange for loyalty, military service, and other obligations. Vassals would swear an oath of allegiance to the king and provide military support when needed. In return, the king would offer protection and support to the vassals. This system helped maintain order and stability in the kingdom, with power and resources flowing from the king to the vassals in exchange for their loyalty and service. **

In Europa Universalis 4, you can create vassals by conquering territory and then releasing it as a vassal state. To do this, you need to have the "Art of War" expansion. Once you have conquered the territory, go to the diplomacy screen with the nation you want to release as a vassal and select the "Release Nation" option. This will create a new vassal state that is loyal to you and will provide you with income and military support. Keep in mind that creating vassals can also increase your diplomatic relations and may affect your diplomatic reputation. **

Unfree vassals, such as farmers, earned money in the Middle Ages primarily through agricultural work. They would cultivate the land, tend to livestock, and produce goods such as grains, vegetables, and dairy products to sell at local markets or to their feudal lord. Some vassals also engaged in other forms of labor, such as working in the lord's household or on construction projects, in exchange for wages or goods. Additionally, some vassals had the opportunity to engage in crafts or trade to supplement their income, although this was often limited by their feudal obligations. **

Unfree vassals, such as peasants, earned money in the Middle Ages primarily through agricultural work on the land they were granted by their lord. They would cultivate crops, tend to livestock, and perform various tasks related to farming in exchange for a portion of the produce. Some peasants also engaged in crafts or trades during their free time to earn additional income. Additionally, they might have taken on seasonal work for their lord or other landowners to supplement their earnings. **

The king received natural tributes from both the peasants and the vassals. Peasants were required to provide a portion of their agricultural produce or other natural resources to the king as a form of tribute. Vassals, on the other hand, were obligated to provide military service, as well as other forms of support, to the king in exchange for land and protection. Both groups contributed to the king's wealth and power through their tributes and services. **

Sustainability in education refers to the integration of environmental, social, and economic principles into the learning experience. It involves teaching students about the importance of preserving natural resources, promoting social equity, and fostering economic prosperity for future generations. Sustainability in education also encompasses the development of critical thinking skills and a sense of responsibility towards the environment and society. It aims to empower students to become informed and active global citizens who can contribute to creating a more sustainable world. **

In Europa Universalis 4, Junior Partners are countries that are under a personal union with another country, where one country is the senior partner and the other is the junior partner. Vassals are countries that are under the control of another country, but are not part of a personal union. Coalitions are groups of countries that band together to oppose a powerful nation that has expanded aggressively. To obtain Junior Partners, you can either inherit them through royal marriages and events, or force them into a personal union through war. Vassals can be obtained by conquering and then releasing a country as a vassal, or by diplomatically vassalizing a smaller country. Coalitions form when a nation's aggressive expansion causes other countries to join together in opposition. **

In Europa Universalis 4, junior partners are smaller countries that are under the protection or control of a larger country, known as the senior partner. Vassals are similar to junior partners but have more autonomy and can provide military support to their overlord. Coalitions are groups of countries that band together to oppose a powerful nation that has been expanding aggressively. You can obtain junior partners by using the diplomatic actions of personal union or vassalization. Personal union can be achieved through royal marriages and claiming thrones, while vassalization can be done through diplomatic annexation or by winning wars and forcing the target country to become your vassal. Coalitions are formed when multiple countries feel threatened by your expansion, so it is important to manage aggressive expansion and improve relations with potential coalition members to prevent them from joining forces against you. **