What were the various changes that had taken place in Europe at the beginning of the middle ages ? What were the main characteristics of the middle ages in Europe?

Changes from what??

Here are many websites about the middle ages:
http://www.google.com/search?q=main+characteristics+of+the+middle+ages&ie=utf-8&oe=utf-8&aq=t&client=firefox-a&rlz=1R1GGHP_en___US434

Read lots and take good notes.

To understand the various changes that occurred at the beginning of the Middle Ages in Europe and the main characteristics of this time period, it is important to refer to historical knowledge. There are several ways to explore this topic:

1. Books and Historical Sources: Consult books or online resources dedicated to the history of Europe during the Middle Ages. Look for books on medieval Europe or specific regions, such as "The Penguin History of Medieval Europe" by Maurice Keen or "The Oxford Illustrated History of Medieval Europe" edited by George Holmes. These sources provide detailed information about the changes and characteristics of the early Middle Ages.

2. Academic Journals and Articles: Academic journals and articles can offer specialized and in-depth analysis of specific aspects of the early Middle Ages. Access databases like JSTOR or scholarly search engines like Google Scholar and search for articles related to the changes and main characteristics of Europe in the early Middle Ages.

3. Online Courses and Lectures: Many renowned universities and educational platforms offer online courses or lectures on the Middle Ages. Websites like Coursera, edX, or The Great Courses offer free or paid courses taught by expert professors. Enrolling in a course or watching lectures can give you a comprehensive understanding of the topic.

4. Museums and Exhibitions: Visit museums or historical exhibitions that focus on the Middle Ages. These institutions often provide educational materials and displays that highlight the changes and main characteristics of the period.

By utilizing these resources, you will be able to gather information on the various changes that took place at the beginning of the Middle Ages in Europe, such as the fall of the Western Roman Empire, the rise of feudalism, the spread of Christianity, and the increasing influence of Germanic tribes. Furthermore, you can learn about the main characteristics of the Middle Ages, including the dominance of the feudal system, the importance of the Catholic Church, the rise of chivalry, the limited social mobility, and the economic and cultural influence of the Byzantine Empire.