The use of the hashtag as a Twitter tool to denote a specific topic in order for the masses to follow along turns 10 years old today, having first been suggested (in a Tweet, naturally) by Silicon Valley regular and early adopter Chris Messina back in 2007. Here’s a little history on its evolution from the humble numerical sign to the social media giant it is today.

1. IT COMES FROM THE LATIN TERM FOR “POUND WEIGHT.”

There’s no definitive origin story for the hash (or pound) symbol, but one belief is that when 14th-century Latin began to abbreviate the term for pound weight—libra pondo—to “lb,” a horizontal slash was added to denote the letters were connected. (The bar was called a tittle.) As people began to write more quickly, the letters and the tittle became amalgamated, eventually morphing into the symbol we see today.

2. IT SHOULD ACTUALLY BE CALLED AN OCTOTHORPETAG.

The symbol portion of the hashtag eventually made its way to dial-button telephones, the result of AT&T looking forward to phones interacting with computers. In order to complete a square keypad with 10 digits (including 0), they added the numerical sign and an asterisk. AT&T employee Don MacPherson thought the sign needed a more official name, so he chose Octothorpe—“octo” because it has eight points, and “thorpe” because he was a fan of football hero Jim Thorpe.

3. TWITTER WASN’T BIG ON THE IDEA AT FIRST.

When web marketer Messina had the notion to add hashtags to keep track of conversations, he stopped by Twitter’s offices to make an informal pitch. He came at a bad time: Co-founder Biz Stone was trying to get the software back online after a crash and dismissed the idea with a “Sure, we’ll get right on that” burn. Undeterred, Messina started using them and the habit caught on.

4. IT’S IN THE OXFORD DICTIONARY.

By 2014, respect for the hashtag had grown to the point where the venerable Oxford English Dictionary gave the word its stamp of approval. Their entry: "hashtag n. (on social media web sites and applications) a word or phrase preceded by a hash and used to identify messages relating to a specific topic; (also) the hash symbol itself, when used in this way."

5. THERE ARE SOME HASHTAG ALL-TIMERS.

Hashtags can highlight interest in everything from political movements to breaking news stories, but the frequency of their use is often tied into popular culture. The most popular TV-related tag has been #TheWalkingDead; #StarWars sees a lot of action; and #NFL dominates sports-related Tweets.