a background process (pronounced "demon") that carries out tasks on behalf of every user. Daemons spend most of their time sleeping until something comes along which requires their help. A UNIX system has a lot of daemons.
a database is the name given to the combination of a program that can manipulate data, together with the data that it acts upon.
a record is a set of data about a person or item. Name, telephone number and postcode is an example of such a set.
a field is one part of that record; the postcode for example.
a delimiter character separates each field from the field preceding it and the field that follows it. A colon (:) is often used as a field delimiter.
a key is the field or part of a field that the program uses when it acts on the data.
a value to which some variable is automatically set, unless an alternative value is provided by the user.