Think of it as:
* A digest: A shorter, easier-to-understand version of something.
* A collection: A gathering of important information or concepts from different sources.
* A handbook: A practical guide to a specific topic, containing essential information.
Examples of compendiums:
* A compendium of Shakespeare's sonnets: A collection of all his sonnets in one volume.
* A compendium of medical knowledge: A summary of important medical facts and procedures for students.
* A compendium of travel tips: A collection of useful advice for planning and taking trips.
In short, a compendium is a valuable resource for anyone who wants to quickly understand a complex topic or get a concise overview of a large amount of information.