Learn in the textbookUnits of Information and the Digitization Process
DefinitionA bit (ビット) is the smallest unit of information, and it represents only one of two values: 0 or 1.
ExplanationEach extra bit lets every existing arrangement be followed by either 0 or 1, so the number of patterns that can be told apart doubles. That is why n bits can represent 2 to the n combinations. When characters and the like are written as bit strings, the arrangement of 0s and 1s assigned to one character is called its code.
AnalogyA single light switch in a room is either on or off, but put three switches side by side and the on-off combinations grow to eight.
Memory hookBit is short for binary digit, so reading it as "one binary digit" reminds you that it has only two possible values.