Silicon is a metalloid, which means it is a type of metal but has some nonmetal qualities depending on what element it is reacting with. An example of this would be the fact that silicon is not a good conductor of electricity.
Silicon is part of group 14 on the periodic table, which is considered a metalloid group. The group includes carbon, germanium, tin, lead and flerovium. Out of this group, carbon is the only one considered a full nonmetal.
Silicon has many of the aspects of metal, meaning it bends but does not break, does well under heat, is malleable, has luster and has a high melting point. The lack of conductivity in silicon keeps it from being fully classified as a metal.
While silicon is the second most abundant element in the Earth's crust, it is harder to find as a pure free element. It is mostly found in dust and sand on Earth, while in the universe, it is found in the crusts of other planets and planetoids.
One of the most important roles that silicon plays in the modern world is in technology. Purified silicon is used in semiconductor electronics and makes up much of the integrated circuits in computers, meaning that much of the technology we use is dependent upon silicon.