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 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. **

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. **

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. **

Renewable energy is energy that is collected from resources that are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. These sources of energy are considered sustainable because they are naturally replenished and do not deplete finite resources. Renewable energy is seen as a cleaner and more environmentally friendly alternative to fossil fuels, as it produces lower levels of greenhouse gas emissions and reduces our dependence on non-renewable resources. **

Yes, solar energy is renewable because it is derived from the sun, which is a virtually limitless source of energy. The sun's energy is constantly being replenished and will continue to do so for billions of years. This makes solar energy a sustainable and renewable source of power that can be harnessed for electricity generation and other applications. **

Renewable resources are natural resources that can be replenished or regenerated over time, such as sunlight, wind, and water. Renewable energy sources are sources of energy that come from these renewable resources, such as solar power, wind power, hydropower, and geothermal energy. These sources of energy are considered sustainable and environmentally friendly because they do not deplete the Earth's resources and produce lower levels of greenhouse gas emissions compared to fossil fuels. **