Internal computer manipulation is not data, a person needs to be involved. Logical versus Physical Data. Logical data is the way the data appears to the user. Physical data is the way it is stored, computer memory, files, and directories. Normally data is stored in a sequence of numbers called binary digits or bits.
Fields are the values for each attribute.
Fields may be fixed or variable length. Fixed length fields are normally used for data that is used for mathematical or other calculations, such as pixel values, where accuracy in data entry is important. Variable length fields are used or highly variable data such as descriptive data. Database data is normally access either by sequential or random access methods. Sequential access is accomplished when data is arranged in contiguous, linear fashion.