Thunderforge makes a compelling argument that the tag length limit should be longer than 25 characters.

Tim and animuson are quite right that shorter tags are generally better; regardless, supporting arbitrarily long tag names is out of the question for the foreseeable future - there are too many things that would break, that people would intentionally break. I guarantee you, the minute we were to allow 100-character tags some jackass would make a new programming language named bwaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaargh and CodeGolf would make it the topic of 80 new questions and everything would go to hell...

...But there are clearly quite a few legit, not-at-all-trolling uses for tags that run from 26 to 35 characters. And as luck would have it, the system tolerates 35-character tag-names as of a year or so ago.

So as of this afternoon, the maximum length of a tag name is 35 characters on all sites. Use those extra 10 characters wisely!

Thunderforge makes a compelling argument that the tag length limit should be longer than 25 characters.

Tim and animuson are quite right that shorter tags are generally better; regardless, supporting arbitrarily long tag names is out of the question for the foreseeable future - there are too many things that would break, that people would intentionally break. I guarantee you, the minute we were to allow 100-character tags some jackass would make a new programming language named bwaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaargh and CodeGolf would make it the topic of 80 new questions and everything would go to hell...

...But there are clearly quite a few legit, not-at-all-trolling uses for tags that run from 26 to 35 characters. And as luck would have it, the system tolerates 35-character tag-names as of a year or so ago.

So as of this afternoon, the maximum length of a tag name is 35 characters on all sites. Use those extra 10 characters wisely!