Tag 的使用确实有点儿泛滥了！最早的搜索引擎，就是基于 Tag 展开搜索的，只不过那时候的 Tag 指的是 HTML 的 meta 标签，这已经被证明是不成功的。现在在 Web2.0 下，Tag 已经成为每个应用必不可少的 feature，我们到底应该如何有效地使用 Tag 呢，这篇文章以批评的视角对 Tag 的使用做了一些分析，值得认真阅读！

以下是转载内容，原文在这里，http://glinden.blogspot.com/2006/02/manual-vs-automated-tagging.html。

Rich Skrenta of Topix.net posted a good critique of manual tagging of documents:

Tags aren’t a panacea, since they’re excessively vulnerable to spam, and the items which should belong to the same categories will get different tags from different users. Which is it, “topixnet”? or “topix”?

They’re uniquely valuable in a system like Flickr since photos don’t have any text of their own to keyword search, so getting the user to add any searchable text at all is a big win. You can ask users to caption their photos but often putting just a word or two is easier so the participation level is higher.

But if you have the full text of the web, or blogosphere, or whatever, the marginal utility of the “keywords” tag on the document seems to be rather low. To deal with spam and relevance issues, the search interface for a large collection needs to be appropriately skeptical about what documents are claiming to be about.

This reminds me of what Danny Sullivan said about manually tagging documents:

All the interest (dare I say hype) is largely ignoring the fact that we’ve had tagging on the web for going on 10 years, and the experience on the search side is that it can’t be trusted.

The meta keywords tag has been around for nearly a decade. The idea behind it in part was that people could use the tag to classify what their pages are about.

The data is largely useless … Thinking that tagging would lead to top rankings, some people misused the tag. Other people didn’t misuse the tag intentionally, but they might poorly describe their pages.

And later went on to say:

Wide-open tagging, where anyone can get their pages to the top of a list just by labeling it so, is going to be a giant spam magnet.

Stephen Green at Sun summarizes it well:

[Tagging is] not really a new way of indexing documents, it’s actually an old way that didn’t work very well.

The real test of manual tagging of documents will be when these tagging tools become large enough to drive substantial traffic to websites.

Right now, these tools mostly are used by early adopters. This small, dedicated, loyal audience tends to behave well because there is little incentive to do otherwise.

If the tools become more popular, the incentive to manipulate them will increase. The community-generated tags will become less and less reliable as spammers enter seeking traffic and profit.

This will be the real challenge to manual document tagging. It remains to be seen whether the wisdom of the crowd can prevail over the deceptions of the scammers.