Tags are a way for a machine to know which words in an article most accurately represents the content of the post. They are used by many networks and systems (including Passle) to recommend content to users, based on posts they have previously read or written.
Whilst it's an imperfect system, what it means is that if you don't tag your content, many of the machines will simply not be able to promote you as effectively as if it were.
So, if you want more reads, shares and feedback, be sure to tag your content.
In information systems, a tag is a non-hierarchical keyword or term assigned to a piece of information (such as an Internet bookmark, digital image, or computer file). This kind of metadata helps describe an item and allows it to be found again by browsing or searching. Tags are generally chosen informally and personally by the item's creator or by its viewer, depending on the system. Tagging was popularized by websites associated with Web 2.0 and is an important feature of many Web 2.0 services. It is now also part of some desktop software.