The more you own, the harder it is to remember.
You do not catalog hundreds of books, records, tools, or household items just to make a list. You do it so you can check what you already own, pull up the details when you need them, and stop relying on memory for a collection that has outgrown it.
Before you buy
Check whether you already own it and which copy, edition, release, or version is at home.
When you need the details
Pull up the model, serial number, condition, purchase information, photos, files, notes, or links you kept with the item.
When the collection gets big
Browse the collection you have actually built instead of trying to reconstruct it from memory.
When something changes
Have a record ready for repair, replacement, resale, moving, loss, or insurance documentation.