All data in Prolog are expressed as terms. A term is either a constant , a variable or a compound term , including lists . White Space White space consists of blanks, tabs and newline characters. White space can be placed anywhere before or after a term, operator, bracket, comma, etc.
White space breaks an atom or integer.
Comments Comments are also considered white space since they are ignored as part of the program text. Unlike other programming languages, a variable in Prolog is not a storage location. It is just name given to some value. Compound Terms Data structures in Prolog are built from compound terms. An important class of data structures are the lists.