What # means
Read the context: number label, topic tag, or keypad instruction. Before a numeral, #7 reads as “number seven” on a list, door, or roster.
In code or markup—text with formatting instructions—the hash has a meaning set by that language. A # next to a word is not automatically a social-media tag.
How do hashtags work?
In social posts, # introduces a topic label. The label tells you what the post is about.
As of 2026, X uses hashtags to index topics and link to posts sharing a tag. Spaces and punctuation interrupt the tag: #music works, but #good music tags only good, leaving music outside it.
What does press pound mean?
Press the # key on the telephone keypad. Follow the menu’s instruction about when to press it; its action depends on the menu.
Use “hashtag” for social tags, “number sign” for number labels, and “pound” when following phone instructions.
The musical sharp ♯ is a different character, not a decorative replacement for #.
Don't confuse it with
2Combination ideas
2Questions people ask
1Why does # show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type #
#\0023Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.