There's many reasons!
Here are a few examples...
You might use tags to allow your users to click through for 'more information' on a traditional web page. You can read about how Origin Energy used tags for this purposes here.
Or, you might like be interested in offering a 'click-to-buy' eCommerce option for your users - linking social posts to products in a 'social catalogue'. Read about how Wanted Shoes used tagging for this purpose.
Want more information? We're doing some very interesting work in this space right now, read about our latest case studies here. For any further questions or queries, please send an email to email@example.com or submit a request and our support team will get back to you.