#whyisitcalled a hashtag?

and not a number sign
as in “#3”?
(or n-o period 3?)

For that matter,
why is it a “pound sign”?
(as in “Please enter your password,
followed by the pound sign?”
(my son did not weigh
7#’s 3 oz.
it was lbs., thank you.)

You’re calling it a hashtag
for tweeters who
twitter (or tweet?
yes, tweet……..
but that’s a bird)

Maybe it’s a hashtag as in
corned beefed hash–
in front of the tag?
as in, “tag, you’re it?”
as in….oh, I give up.

just tell me
why is it called a hashtag?