Hashtag
A keyword prefixed with # that groups posts on the same topic and makes them discoverable.
Hashtags started on Twitter in 2007 and are now standard on Instagram, TikTok, LinkedIn, Threads, Bluesky, and Pinterest. They serve two purposes: discovery (people browsing #cooking find your cooking post) and topic-signaling (the algorithm understands your post is about X). In 2026, hashtag strategy diverges by platform: Instagram now recommends 3-5 hashtags max (no more spam-clouds of 30), TikTok wants 3-4 specific niche tags, LinkedIn 3 broad tags, X is mostly irrelevant for organic reach. Branded hashtags (your own #YourBrand) build a community archive but rarely drive new traffic.