SWI-Prolog provides an online help system that covers this manual. If 
the XPCE graphics system is available, online help opens a graphical 
window. Otherwise the documentation is shown in the Prolog console. The 
help system is controlled by the predicates below. Note that this help 
system only covers the core SWI-Prolog manual. The website12http://www.swi-prolog.org 
provides an integrated manual that covers the core system as well as all 
standard extension packages. It is possible to install the SWI-Prolog 
website locally by cloning the website repository
git://www.swi-prolog.org/home/pl/git/plweb.git 
and following the instructions in the README file.
help(help/1).| <Name>/<Arity> | Give help on specified predicate | 
| <Name> | Give help on named predicate with any arity or C interface function with that name | 
| <Section> | Display 
specified section. Section numbers are dash-separated numbers: 2-3refers to section 2.3 of the manual. Section numbers are obtained using apropos/1. | 
Examples:
| ?- help(assert). | Give help on predicate assert | 
| ?- help(3-4). | Display section 3.4 of the manual | 
| ?- help('PL_retry'). | Give help on interface function PL_retry() | 
See also apropos/1 and the SWI-Prolog home page at http://www.swi-prolog.org, which provides a FAQ, an HTML version of the manual for online browsing, and HTML and PDF versions for downloading.
| ?- apropos(file). | Display predicates, functions and sections that have `file' (or `File', etc.) in their summary description. |