A standard YouTube video ID contains 11 characters.
The ID is the compact, case-sensitive string that identifies an individual video in YouTube URLs. In a typical watch link, it appears after “v=”; in a shortened youtu.be link, it follows the slash. An example is the 11-character string commonly seen in a video address, rather than the video’s title, channel name, or playlist ID.
YouTube video IDs use a URL-friendly Base64-style character set: uppercase and lowercase letters, numerals, hyphens, and underscores. With 64 possible characters in each position, 11 positions create a theoretical space of 64^11, or roughly 73.8 quintillion combinations.
The main mix-up is confusing a video ID with other YouTube identifiers. Channel IDs and playlist IDs have different formats and lengths, and a full video URL also includes domains, parameters, and sometimes timestamps. Shorts, embedded videos, and youtu.be links still use the same underlying 11-character video identifier.