A pattern is a careful description of a perennial solution to a recurring problem within a building context, describing one of the configurations which brings life to a building. A pattern language is a network of patterns that call upon one another. An individual house might, for example, call upon the patterns described under the names of half-hidden garden, light from two sides in every room, variation of ceiling height, bed alcove, etc. Patterns help us remember insights and knowledge about design and can be used in combination to create designs.
The use of patterns can be and is widespread and not limited to professionals.
253 patterns are available to you on the site. You may find them by going to the pattern language volume and exploring it.