The CD-ROM works with any Java-enabled browser (Internet Explorer 4.0 and Netscape Communicator 4.0.) It includes the full text of the printed book along with the richness of hypertext links to get the most out of patterns quickly. (Two versions of the text, one for 640 x 480 resolution and one for higher resolutions, are provided.) Patterns are higher-order designs, which occur repeatedly in object-oriented design. The heart of this title is the "pattern catalog" of 23 basic patterns, ranging from creational patterns, such as Factory and Builder, and structural patterns, such as Facade and Flyweight, to behavioral patterns, such as Command and Mediator. The CD-ROM details each design element along with reasons to use it and sample code in Smalltalk and C++. (With the online version, you can even cut and paste sample code into your programs.) You can use the Java search engine to search the CD-ROM for keywords, and the online version lets you cross-reference patterns easily. All in all, the Design Patterns CD is an appealing new version of one of the most essential texts for object-oriented developers.