A knowledge base is a self-serve online library of information about a product, service, department, or topic.
The data in your knowledge base can be from anywhere, but usually comes from several contributors who are well versed on the subject - enough to give you all the details. Subjects range from the ins and outs of your HR or Legal department to how a new product, hardware, or software works. The knowledge base can include FAQs, troubleshooting guides, and any other nitty gritty details you may want or need to know.