The role of information and communication technologies (ICT) in education is nowadays well recognised. The "Web Geometry Laboratory," is an e-learning, collaborative and adaptive, Web environment for geometry, integrating a well known dynamic geometry system. In a collaborative session, teachers and students, engaged in solving collaboratively a given set of problems, can exchange geometrical and textual information between them. In a normal work session (stand-alone mode), all the geometric steps done by the students are recorded, allowing, in a latter stage, their teachers to "play back" the students sessions. This information, alongside the navigation and chat information, can be used, later on, to assert the students level of geometric knowledge, adjusting the teaching strategies to each individual student. Teachers can register and begin using the public servers, defining students, preparing materials to be released to the students, open collaborative sessions, etc. Students can work in "WGL," defining his/her own working space, sharing geometric constructions between themselves. From the case studies already conducted it was possible to conclude that, using "WGL," the students improved their achievement in mathematics, in the classroom and doing homework. In this paper an in-depth, full description of the "WGL" system in its current version, is made, covering all the features and functioning modes, from the perspective of teachers and students.