Instagram introduced hashtags in January 2011 to help users discover photos and one another. The feature gave posts a searchable topic label by placing the hash symbol before a word or phrase, such as #travel or #sunset.
Hashtags helped Instagram grow from a simple photo feed into an interest-discovery network. Users could attach a relevant tag to a picture, then browse other posts carrying the same label. That made it easier to find communities and subjects beyond the accounts a person already followed. Instagram encouraged specific, meaningful tags rather than generic labels such as “photo.”
A common mix-up is confusing hashtags with mentions. A mention uses the @ symbol to identify or link to an account, while a hashtag categorizes content by topic. Geotags instead associate a post with a location, and stickers are visual or interactive additions rather than the original discovery system described here.
The idea was not invented by Instagram: Chris Messina proposed using the hash symbol for online groupings in a 2007 tweet. Instagram adopted the feature in 2011, helping make hashtags central to photo-sharing culture.