Metadata

Metadata is everything written around a video rather than shown inside it: title, description, the tags box, category, language, and the subtitle and caption fields. Some of it is aimed at viewers. Some of it is machine-read. A common mistake is treating these fields as a growth lever in themselves, so descriptions fill with keyword lists and the tags box gets stuffed with near-duplicates. Accurate, readable fields help YouTube work out what the video covers and help a viewer decide whether to watch. Keyword volume is a different question. A description written for a scraper reads badly to the person who opens it.