address: a number identifying a storage location from which data are to be
retrieved or inserted.
character: smallest unit recognizable to humans (letter or number).
byte: eight bits treated as a unit; memory needed to store a single letter or
word: a set of characters occupying one storage location and treated as a unit.
record: a group of logically related items treated as a unit (see also figure 3-2).
Figure 2-35. Bit vs. byte.
Figure 2-36. Each unit in main storage has a unique address.