One of the most popular forms of learning is through reading and for years we have used hard copy documents as the main material to learn. With the advent of the Internet and the fast development of new technologies, new tools have been developed to assist the learning process. However, reading is still the main learning method that is an individual activity. In this paper we propose a highlighting tool that enables the reading and learning process to become a collaborative and shared activity. In other words, the highlighting tool supports the so-called active-reading, a well-known and efficient means of learning. The highlighting tool brings to the digital environment the same metaphor of the traditional highlight marker and puts it in a social context. It enables users to emphasize certain portions of digital learning objects. Furthermore, it provides students, tutors, course coordinators and educational institutions new possibilities in the teaching and learning process. In this work we expose the first quantitative and qualitative results regarding the use of the highlight tool by over 750 students through 8 weeks of courses. The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-33642-3_6.