Bit is a contraction of ‘binary digit’ and is the smallest unit of measurement for computer data. As the name suggests, bits are counted in base-2, so the value of any given bit will be either 0 or 1 (its value being defined by whether it is above or below a set level of electrical charge within a capacitor).

Eight bits (called a byte) are required for a single alphanumeric character. Higher multiples used to measure data are the kilobyte (1,024 bytes), the megabyte (1,048,576 bytes), the gigabyte (1,073,741,824 bytes) and the terabyte (1,000 gigabytes).

Bandwidth (how fast data travels) is normally measured in bits per second.