Blackwell Synergy is a pay-per-use or subscription service but a generous amount of material, customizing tools and info are provided for free to any user. Extremely valuable is the CrossRef Pilot Service, improving BS linking features.
Access to the full-text journal articles is available through library subscriptions worldwide, and to individual subscribers and society members, as well as through an article pay-per-view service
Abstracts, metadata and tables of contents of all articles are retrievable for free. Many other articles, after a certain time, become also freely accessible. Free samples and some open access journals are also available
Reference links and citing article links allow users to move back and forth through the articles and research fields both within Blackwell Synergy and other databases