I am designing a website that every article in it is related somehow with other articles ... I attend to do the relation by tagging the articles .. but some of the team suggested to do the relation with a predefined Vocabulary and name it Controlled vocab while our developer like the most the keywords.
So I wonder what is the difference and where should I use one but the others? and is is the best solution making relations between articles with just tagging?
Controlled vocabulary means that within the system some predefined terms are used for organisation - users cannot add their own terms.
Controlled vocabulary within Information Architecture is subdivided into:
If tags are predefined by the system and users can't change them, they serve as controlled vocabulary. If users can change (add to) them, they contribute to a 'folksonomy'.
Keyword, on the other hand, are key words related to something. Involving highly contextual nature (rather than organisational), you could argue that an article's keywords may involve such diversity that users must be able to change these.
Tags and keywords within your context can be very similar. But you can argue that you can tag a task as important, but important is not a keyword in such case.
The problem with folksonomies is that they needs moderation, analysis and some tiding up; like marking 'IA' as the same as 'Information architecture'. Ideally, instead of doing this job yourself, you provide users with means to do it.
The problem with controlled vocabularies is that you force users to use a constrained list of terms, which are often based on assumption rather than research. Also, controlled vocabularies are little dynamic - shall new terms emerge, you'd have to add them yourself.
I'm not sure you use the term correctly, because relations are often realised by links (think wikipedia). Tags and controlled vocabularies are classification mechanisms, not relation mechanism (other than the obvious fact that all items under a particular class are related). But the two are rather different concept. So was it classification you meant?
If you are creating the categories use predefined options. This will alleviate the creation of duplicates caused by spelling errors, errors in capitalization or similar terms that can be introduced by allowing your audience to tag your content. However by defining set categories you miss out on the value of tagging. Allowing your customer to define your content via tags can help you to better understand how your audience understands the content. They may use terms or think of categories that don't match options you have created. Trying to select from a list and not finding the right option can cause friction in the use of your product or service.
