Catalogue
A database recording every image in a collection along with its metadata, previews and editing instructions.
Measured in
count
In depth
A catalogue holds references to files rather than the files themselves, which is what lets it search an archive spread across several drives instantly. Its weakness is that it is a single point of failure and usually a proprietary format, which is why regular catalogue backups and metadata written to sidecars are both necessary.
Examples in practice
A catalogue of 300,000 images filters to 40 candidates on three criteria in under a second.