Following Implement a Tag Black List, I would like to know what exactly it means for a tag to be marked as blocked (formerly blacklisted) on a Stack Exchange site.
A blocked tag (formerly blacklisted tag) is a tag that can no longer be used in a specific Stack Exchange community. Blocked tags are automatically prevented from being used or created on a site.
A tag may be marked as blocked for a number of reasons. It may be a redundant tag, such as a game tag on Arqade or a programming tag on Stack Overflow. It may be a meta tag describing the character rather than the topic of a question. In general, there is usually a shared consensus that these tags add little to no value to a question.
Generally, tags are only blocked if they have been recreated and removed multiple times despite such consensus. Some communities may also block a tag if a significant number of questions are using it, to prevent new questions from using the tag while the community continues to manually remove the tag from existing posts which use it.
Examples of blocked tags include, but are not limited to:
Tags can only be added to the block list by Stack Exchange employees. However, you can request a tag be blocked by posting a request on the relevant per-site meta. (See How should we make requests to block tags? for more information).
It's possible to block tags that already currently exist, and blocking a tag by itself does not automatically remove the tag from questions previously using it. However, if you edit a question that currently uses a blocked tag, you will be prompted to remove it before you can submit your edit.
blacklist when specifically connected to programming, its replacement "block list", has the added bonus inasmuch its meaning is clearer. But I wouldn't recommend or worry about editing out every mention of "blacklist" when it's used as a normal verb, e.g. “Rude, vulgar terms such as c___ are blacklisted on SE”.
Commented
Aug 7, 2020 at 6:16