At first sight the Universe appears to be made of "matter"; and we have a fairly good understanding of this matter. The basic building blocks are quarks and leptons; and a rather well understood theory describes how these particles interact via the strong, weak, and electromagnetic forces. However, there is evidence that this "matter" only constitutes 5% of the mass of the universe. Another 35% may consist of unobserved forms of matter, "dark matter". The remaining 60% of the mass of the Universe seems to be "dark energy"; energy associated with the vacuum, which may be causing the expansion of the Universe to accelerate. What we have so far observed and understood may actually be a rather minor aspect of the Universe. I will talk about some of these ideas, and describe experiments, which U of T people are involved in, which may actually produce the particles of "dark matter", and throw light on the origin of mass, and of the energy associated with the vacuum.