Asset Organization, Search, and Collections
Organization happens through folder hierarchy, tags (the cq:tags taxonomy under /content/cq:tags), and collections. Know the three collection types: static collections (manual membership, stored as sling:members or references), smart collections (dynamic, driven by a saved search query), and the distinction that smart collections re-evaluate membership at query time while static ones are fixed.
Search in AEM Assets is backed by the Oak query engine (JCR-SQL2, XPath, or the QueryBuilder API). Full-text search uses the Lucene property index. Understand that Assets search uses the dam:Asset type and that metadata fields are searchable only if indexed. The QueryBuilder is the developer's tool: predicates like path, type, fulltext, property, and daterange compose a query. A classic trap is writing a fulltext predicate when the requirement is an exact property match, or forgetting type=dam:Asset and getting pages back.
Tags vs. folders: folders are for hierarchy and permissions; tags are for cross-cutting classification and drive smart collections and search facets. Traps: (1) assuming a smart collection stores asset references - it stores a query; (2) thinking deleting a tag from the taxonomy removes it from assets (it orphans the reference); (3) confusing search facets (UI) with the underlying index configuration. Rule of thumb: if membership must update automatically as new assets match criteria, it is a smart collection; otherwise static.