In computing, a bit (short for "binary digit") is the smallest unit of digital information. It can have a value of either 0 or 1 and is the basic building block of all digital data. A bit is always in one of two physical states, similar to an on/off light switch, and the state is represented by a single binary value, usually a 0 or 1. Bits are stored in memory through the use of capacitors that hold electrical charges, and the charge determines the state of each bit, which, in turn, determines the bits value. Although a computer might be able to test and manipulate data at the bit level, most systems process and store data in bytes. A byte is a sequence of eight bits that are treated as a single unit. Bytes are usually used to represent larger amounts of information, such as letters, numbers, or symbols. The names and abbreviations for numbers of bytes are easily confused with the notations for bits, and the abbreviations for numbers of bits use a lower-case "b" instead of an upper-case "B".