Founded in 2005 YouTube has became the most fast growing stream service, that has a great impact on the internet traffic distribution. Thus understanding YouTube's characteristics is crucial to network providers. In this survey we are going to present the factors that impact user's satisfaction, in other meaning the impact on the Quality of experience(QoE). Furthermore we will discuss how to determine the influencing factors on YouTube, how to measure its quality and how to improve it. Tomorrow YouTube will have to adapt to the changes that will occur because our environment is changing from regular to smart digital one.