1. We discussed forms of data and processes relevant to an electronic till in a supermarket. In particular, we introduced the idea of a sequence of data items.
2. A number of fundamental forms of data were introduced. We distinguished two types of number: integers (positive or negative whole numbers, or 0), and real numbers (thought of as decimal numbers and approximated in computers as floating point numbers). Characters may be thought of as symbols that may be entered from a computer keyboard by a single keystroke. Each character is associated with an integer code and we introduced one such encoding called the ASCII code. The Boolean values true and false form another fundamental form of data.
Data may be structured in a collection. Different forms of collection are possible. We looked at two: sets and sequences. In a sequence, the order in which the items appear in the collection is important and an item may appear more than once. In a set, one is only interested in the different items appearing in the collection, and the order in which these items are listed is of no significance, nor is repetition of an item.