---
title: "Tag (#tag) · tnotes"
description: "A tag is a keyword attached to a note, usually written inline as #word, that groups notes across folders and can be filtered on."
canonical: https://tnotes.app/glossary/tag
---

[glossary](/glossary) / tag

# Tag (#tag)

A tag is a keyword attached to a note, usually written inline as #word, that groups notes across folders and can be filtered on.

A tag is a label on a note. Unlike a folder, a note can carry many tags, and a tag can span every folder. In Markdown notes the usual form is an inline hashtag, `#meeting`, written anywhere in the text; some tools also or instead take a list in front matter.

## Origin

Tagging as user-assigned keywords spread through the 2000s web (del.icio.us bookmarks, Flickr photos) as an alternative to fixed categories. The `#` prefix comes from IRC channel names by way of Twitter: Chris Messina proposed `#barcamp`\-style groups in an August 2007 tweet, and Twitter started hyperlinking hashtags to search in 2009 ([Wikipedia: Hashtag](https://en.wikipedia.org/wiki/Hashtag)). Note tools adopted the inline form because it needs no UI: the tag is part of the text, survives copy and paste, and is visible in any editor.

## How it works

The tool scans each note for `#` followed by a word, builds an index from tag to notes, and offers a filter or search operator. Nested tags extend the word with slashes, `#work/project`, so that filtering on `#work` also matches its children; Obsidian documents this exact behaviour and rule set: letters, numbers, `_`, `-` and `/`, at least one non-digit, case-insensitive ([Obsidian: Tags](https://help.obsidian.md/tags)). Completion after typing `#` keeps spelling consistent, which matters because `#meeting` and `#meetings` are two tags.

## Pitfalls

`#` is overloaded in Markdown. `# Heading` at the start of a line is a heading, `#1984` may be an issue number, and a `#` inside a code span is code. Parsers differ on which of these they treat as tags. Tags do not carry meaning beyond their name, so a taxonomy drifts: `#todo`, `#task` and `#tasks` accumulate unless there is completion or a tag list to check against. Front-matter tags and inline tags are two systems, and a tool that reads only one will miss the other. Shell users hit one more: `#` starts a comment, so `--tag '#work'` needs quotes.

## In other tools

Obsidian reads inline `#tags` and a `tags` list in properties, with a tags view for browsing. jrnl uses `@` as its tag symbol precisely because `#` is reserved in shells, and warns when a new tag looks like a typo of an existing one ([jrnl docs](https://jrnl.sh/en/stable/usage/)). nb accepts `--tags tag1,tag2` on `nb add` and `#tagging` in the text ([nb README](https://github.com/xwmx/nb)).

## In tnotes

tnotes parses `#tags` from the note text, including nested ones like `#work/project`. There is no tag field; the text is the source of truth. In the editor, typing `#` then `tab` completes from existing tags, and `ctrl+click` on a tag filters the list to it. Tags are highlighted in the `theme.tag` colour (`green` by default) when `editor.highlight = "color"`.

The CLI filters and creates by tag; a leading `#` is stripped so quoting is harmless:

```
tnotes ls --tag work
tnotes search "invoice" --tag '#work/acme' --json
tnotes new "Standup" --tag work
```

`ls --json` includes a `tags` array per note. A `tags:` line in a header is not parsed; write the tag inline instead. See [/docs/cli](/docs/cli) and [/glossary/frontmatter](/glossary/frontmatter).

## Related terms

-   [Daily note](/glossary/daily-note)
-   [Front matter](/glossary/frontmatter)
-   [Vault](/glossary/vault)