In SharePoint, metadata is good.  Metadata is very good.  "That's great," you say, "but what the heck is metadata?"

Metadata is data about your data.  Got it?  Good, I'm glad you're going along with me on that.

Ok, ok.  Metadata is information you attach to your SharePoint content that provides contextual clues to the subject, audience, and/or intent of your content.  For an example of metadata, you need to look no further than this blog post.  At the end of it, you'll see that I've applied some "tags" to this post that summarize some of the topics I touch on in this blog post.  Because while the title of this blog summarizes the main topic of the post, it doesn't tell the reader that I'm talking about documents, search, collaboration sites and lists.  The tags I've put on this post do tell you that I mention those topics in this post and give you a better idea of what it covers.

So how does this apply to SharePoint?  As I said above, metadata is a very good thing in SharePoint.  The most obvious benefit is the added context it gives to the consumers of your content when they are looking at it.  But it also drastically improves the discoverability of your content; metadata provides SharePoint with more hooks into the context of your content so that it can easily categorize, crawl, and index. 

Categorization is important because SharePoint doesn't really do folders very well.  We're all very accustomed to using folders; it's how we store our documents in our desktop computers, and on traditional file shares.  But in SharePoint, folders make it harder to find documents.  I highly recommend checking out this post by Michael Reinhart on why I don't think folders are good in SharePoint, Michael says it better than I could and its not worth covering that ground twice.

Search is another big reason why metadata is important.  Tagging your content gives the SharePoint search engine even more context around your content so that it can more accurately display it when it is relevant to a user's search.  This makes it easier for users to effectively find your documents, which (at least to me) is a pretty big deal.

Now the question is: how do I use metadata within a SharePoint site?  I've uploaded my document, but I don't see a whole lot of customization available for the items I input about my document.  The thing you'll want to examine is what columns you currently have in your document library.  Those columns are the values that you're asked to input and/or update when you load a document into your library.  So by adding new columns you can add more information (metadata) about your documents. 

NOTE: I'm using document libraries as an example here; you can add columns to any list in SharePoint to create metadata for the items in that list

One of my favorite tricks is to create a separate list in my site that contains the various values I might assign to my content, and then tie that list to my library for use as metadata.  That way, I have a set list of metadata values I can use when adding content and I can reuse that list across multiple libraries.  It's very, very handy.  The only problem is that while it is easy to do, it is not readily apparent how to pull it off.  Fear not, dear reader.  Mark Miller over at endusersharepoint.com has just done an excellent post walking you through the steps necessary to make this happen.