SAGE, the open source CAS to end all CASs?

SAGE, the 'Software for Algebra and Geometry Experimentation', is an open source computer algebra system (CAS). It comprises and allows access to well known specialized open source CASs like GAP, MAXIMA, PARI/GP, R, SINGULAR etc. and other optional ones. SAGE is highly practical and supports education in mathematics, in many situations and at all levels; like many CASs, it is powerful enough to handle a wide range of mathematical problem ─ in calculus, algebra, numerics, number theory etc. Because it is open source and easily installed or accessed via its splendid web interface, it is available to anyone, any time, anywhere. In this way, it supports instructors to teach and learners to learn and explore mathematics