Star clusters are groups of stars which are gravitation-ally bound. Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young.
Binary system: a system in which information can be expressed by combinations of the digits 0 and 1. to represent codes and data. Since zeros and ones can be easily represented by two voltages, the binary system is the foundation on which digital technology is built. Every digital computer whether a pocket calculator or a mainframe uses the same binary notation.
