What is a Hastag?
A hastag is word or phrase preceded by the hash or pound sign (#) and is used to identify messages on a specific topic.
On Instagram, you can add up to 30 hashtags on a post caption or comment. If your post is visible to the public, then tapping on the hashtag will lead to page that shows all the photos and videos with the same hashtag. For Instagram hashtags, no spaces or special characters are allowed. However, you can add numbers to a hashtag.