Obsidian uses #tag for tags, and while # is the most common character for tags (everyone’s heard of hashtags), it’s not universal and doesn’t fit all workflows.
One of Obsidian’s core tenets is that your data is yours, and it’s just plain-text, but these small things act as a form of data lock-in.
I’m moving my existing “second brain” into Obsidian, but my existing workflow uses # for (physical) locations. For example, my “errands” list might have “#pharmacy: buy xyz”. I don’t want that to be recognized as a tag. I could switch to another character, but I’m already using @ and + as a prefix for other uses, and years of muscle memory is surprisingly hard to get rid of.
I also make notes about music theory, where # is used for “sharp” (a half-tone up from a note). So, writing a scale formula for the Lydian scale would be “1 2 3 #4 5 6 7”. Obsidian doesn’t currently recognize #4 as a tag, but I’m a bit worried the parsing for this will change in the future. You might also write about a #9b11 chord (sharp 9 flat 11), which is recognized as a tag.
Hex colors like #ffffff are also recognized as tags. Same for other hex values (which you might use in notes, in case you’re a programmer).
Maybe you’re a brand manager, and want to write down tweet ideas, but don’t want the hashtags to be tags for the note. Likewise, # is used for channels in IRC, Discord, Slack and other chat programs, maybe you’re writing employee orientation or community guideline documents.
I know I could escape the # character with
\#, but I would very much prefer to just use something like
tag: as an “explicit” tag prefix, and have # just be a regular character.