The goal of SAGE is to create an optimal software environment for research and experimentation in algebra, geometry, number theory, cryptography, and related areas. The speaker started SAGE in 2005 by combining together the very best of existing free software (e.g., Singular, PARI, GAP, Macaulay2, Maxima, gfan, etc), creating interfaces to non-free software (e.g., MAGMA, Maple, Mathematica), and beginning to fill in the gaps with new code. Now many developers have joined him in working on filling these gaps and making SAGE a polished and efficient piece of software. This talk will demo SAGE, and explain how it works.